I have added extra fields and it is working fine but after login when i try to edit the fields they are not saved as expected in the identity db users.
index html: 
@page
@model IndexModel
@{
    ViewData["Title"] = "Profile";
    ViewData["ActivePage"] = ManageNavPages.Index;
}
<h3>@ViewData["Title"]</h3>
<partial name="_StatusMessage" for="StatusMessage" />
<div class="row">
    <div class="col-md-6">
        <form id="profile-form" method="post">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <div class="form-floating">
                <input asp-for="Username" class="form-control" disabled />
                <label asp-for="Username" class="form-label"></label>
            </div>
            <div class="form-floating">
                <input asp-for="Input.Name" class="form-control" />
                <label asp-for="Input.Name" class="form-label"></label>
                <span asp-validation-for="Input.Name" class="text-danger"></span>
            </div>
            <div class="form-floating">
                <input asp-for="Input.Address" class="form-control" />
                <label asp-for="Input.Address" class="form-label"></label>
                <span asp-validation-for="Input.Address" class="text-danger"></span>
            </div>
            <div class="form-floating">
                <input asp-for="Input.PhoneNumber" class="form-control" />
                <label asp-for="Input.PhoneNumber" class="form-label"></label>
                <span asp-validation-for="Input.PhoneNumber" class="text-danger"></span>
            </div>
            <div class="form-floating">
                <input asp-for="Input.City" class="form-control" />
                <label asp-for="Input.City" class="form-label"></label>
                <span asp-validation-for="Input.City" class="text-danger"></span>
            </div>
            <div class="form-floating">
                <input asp-for="Input.PinCode" class="form-control" />
                <label asp-for="Input.PinCode" class="form-label"></label>
                <span asp-validation-for="Input.PinCode" class="text-danger"></span>
            </div>
            <button id="update-profile-button" type="submit" class="w-100 btn btn-lg btn-primary">Save</button>
        </form>
    </div>
</div>
@section Scripts {
    <partial name="_ValidationScriptsPartial" />
}
index cs file:
using System;
using System.ComponentModel.DataAnnotations;
using System.Text.Encodings.Web;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using ShoppingCart2023.Models;
namespace ShoppingCart2023.Areas.Identity.Pages.Account.Manage
{
    public class IndexModel : PageModel
    {
        private readonly UserManager<ApplicationUser> _userManager;
        private readonly SignInManager<ApplicationUser> _signInManager;
        public IndexModel(
            UserManager<ApplicationUser> userManager,
            SignInManager<ApplicationUser> signInManager)
        {
            _userManager = userManager;
            _signInManager = signInManager;
        }
        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        public string Username { get; set; }
        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        [TempData]
        public string StatusMessage { get; set; }
        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        [BindProperty]
        public InputModel Input { get; set; }
        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        public class InputModel
        {
            /// <summary>
            ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
            ///     directly from your code. This API may change or be removed in future releases.
            /// </summary>
            [Phone]
            [Display(Name = "Phone number")]
            public string PhoneNumber { get; set; }
            [Required]
            public string Name { get; set; }
            public string? Address { get; set; }
            public string? City { get; set; }
            public string? PinCode { get; set; }
        }
        private async Task LoadAsync(ApplicationUser user)
        {
            var userName = await _userManager.GetUserNameAsync(user);
            var phoneNumber = await _userManager.GetPhoneNumberAsync(user);
            Username = userName;
            Input = new InputModel
            {
                PhoneNumber = phoneNumber,
                Name = user.Name,
                Address = user.Address,
                City = user.City,
                PinCode = user.PinCode
            };
        }
        public async Task<IActionResult> OnGetAsync()
        {
            var user = await _userManager.GetUserAsync(User);
            if (user == null)
            {
                return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
            }
            await LoadAsync(user);
            return Page();
        }
        public async Task<IActionResult> OnPostAsync()
        {
            var user = await _userManager.GetUserAsync(User);
            if (user == null)
            {
                return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
            }
            if (!ModelState.IsValid)
            {
                await LoadAsync(user);
                return Page();
            }
            var phoneNumber = await _userManager.GetPhoneNumberAsync(user);
            if (Input.PhoneNumber != phoneNumber)
            {
                var setPhoneResult = await _userManager.SetPhoneNumberAsync(user, Input.PhoneNumber);
                if (!setPhoneResult.Succeeded)
                {
                    StatusMessage = "Unexpected error when trying to set phone number.";
                    return RedirectToPage();
                }
            }
            if (Input.Name != user.Name)
                user.Name = Input.Name;
            if (Input.Address != user.Address)
                user.Address = Input.Address;
            if (Input.City != user.City)
                user.City = Input.City;
            if (Input.PinCode != user.PinCode)
                user.PinCode = Input.PinCode;
            await _signInManager.RefreshSignInAsync(user);
            StatusMessage = "Your profile has been updated";
            return RedirectToPage();
        }
    }
}