Modify the Program.cs file as has been done with this snippet of code (see comments).

using Microsoft.AspNetCore.ResponseCompression;

var builder = WebApplication.CreateBuilder(args);

// ...

builder.Services.AddResponseCompression(options =>
{
    options.Providers.Add<BrotliCompressionProvider>();
    options.Providers.Add<GzipCompressionProvider>();
	// NOTE: could also add the DeflateCompressionProvider here
    options.EnableForHttps = true; // NOTE: compress over HTTPS, too
    options.MimeTypes = new string[] { "image/svg+xml", "application/pdf", "application/json", "application/javascript", "application/rtf", "application/xhtml+xml", "application/xml", "text/*", "model/gltf+json" }; // NOTE: add MIME-Types to compress here
});

builder.Services.Configure<BrotliCompressionProviderOptions>(options =>
{
    options.Level = CompressionLevel.Optimal; // NOTE: this takes longer to compress but it is not as aggressive as the Optimal setting when using the compression classes directly
});

builder.Services.Configure<GzipCompressionProviderOptions>(options =>
{
    options.Level = CompressionLevel.Optimal;
});

// ...

var app = builder.Build();
app.UseResponseCompression(); // NOTE: call this soon after the line of "var app = builder.Build();"

// ...

USE THIS UTILITY TO TEST THE HTTP COMPRESSION.

Modify the Startup.cs file. Under the ConfigureServices() method, add the BrotliCompressionProvider and set the compression level to Optimal which is a balance between compression speed and compression ratio. Finally, add the middleware app.UseResponseCompression() BEFORE the other middleware components.

// Startup.cs
using System.IO.Compression;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.ResponseCompression;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace ProjectName
{
	public class Startup
	{
		public Startup(IConfiguration configuration)
		{
			Configuration = configuration;
		}

		public IConfiguration Configuration { get; }

		// This method gets called by the runtime. Use this method to add services to the container.
		public void ConfigureServices(IServiceCollection services)
		{
			services.AddControllersWithViews();
			services.AddResponseCompression(options =>
			{
				options.Providers.Add<BrotliCompressionProvider>();
				options.Providers.Add<GzipCompressionProvider>();
				options.EnableForHttps = true; // OPTIONAL - enable for sites that use HTTPS
				options.MimeTypes = new string[] { "image/svg+xml", "application/*", "text/*" }; // this should compress what needs to be compressed
			});
			services.Configure<BrotliCompressionProviderOptions>(options =>
			{
				options.Level = CompressionLevel.Optimal; // OPTIMAL is just that, not too fast or slow - this may or may not fit all websites' needs
			});
		}

		// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
		public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
		{
			app.UseResponseCompression(); // call this before app.UseStaticFiles(); and other middleware
			if (env.IsDevelopment())
			{
				app.UseDeveloperExceptionPage();
			}
			else
			{
				app.UseExceptionHandler("/Home/Error");
			}

			app.UseStaticFiles();

			app.UseRouting();

			app.UseAuthorization();

			app.UseEndpoints(endpoints =>
			{
				endpoints.MapControllerRoute(
					name: "default",
					pattern: "{controller=Home}/{action=Index}/{id?}");
			});
		}
	}
}

USE THIS UTILITY TO TEST THE HTTP COMPRESSION.

Coding Video

https://youtu.be/ZGvkLK8JrGo