How can Asp Net Core serve html static pages?

I have recently started an Asp .Net Core app. Later I wanted to integrate it with Angular, but first I wanted a mechanism that will 'replace' cshtml with html.

If I change extension from cshtml to html I get this

'InvalidOperationException: The view 'Index' was not found'.

Also I tried in Startup

app.UseStaticFiles();
app.UseMvc(routes =>
{
    routes.MapRoute(
        name: "default",
        template: "{controller=Home}/{action=Index}/{id?}");      
});

but it also didn't work.

Optional is to integrating cshtml layout content with html pages, but I think this is impossible.

So, my question is, can I simply replace all cshtml with html?

Static files are typically located in the web root (wwwroot) folder.By default, that is the only place where we can serve up files directly from the file system.

1.create a html file inside (wwwroot) name index.html

2.install Microsoft.AspNet.StaticFiles package via NuGet

3.Add UseStaticFiles in Startup.cs under Configure methode

public void Configure(IApplicationBuilder app)
{
    app.UseStaticFiles(); // For the wwwroot folder

    // if you want to run outside wwwroot then use this
    //request like http://<app>/StaticFiles/index.html
   /* app.UseStaticFiles(new StaticFileOptions()
    {
        FileProvider = new PhysicalFileProvider(
            Path.Combine(Directory.GetCurrentDirectory(), @"MyStaticFiles")),
        RequestPath = new PathString("/StaticFiles")
    });*/
}

if you want to run Static Files outside wwwroot, then-

public void Configure(IApplicationBuilder app)
{
    app.UseStaticFiles(); // For the wwwroot folder

    //request like http://<app>/StaticFiles/index.html
    app.UseStaticFiles(new StaticFileOptions()
    {
        FileProvider = new PhysicalFileProvider(
            Path.Combine(Directory.GetCurrentDirectory(), @"MyStaticFiles")),
        RequestPath = new PathString("/StaticFiles")
    });
}

your request like http://<app>/StaticFiles/index.html

if you want index.html to be your default file, this is a feature that IIS has always had,then

public void Configure(IApplicationBuilder app)  { 
   app.UseIISPlatformHandler();  
   app.UseDeveloperExceptionPage(); 

   app.UseRuntimeInfoPage();  
   app.UseDefaultFiles(); 
   app.UseStaticFiles();

}

hopefully it's help you. You can more information from this link.