You don’t need to use a library, but it can expedite the process and make it a bit more friendly. The library I use to make rest requests is called RestSharp. It’s easy to use and easy to customize. I also use Newtonsoft in combination with RestSharp to deserialize the result. RestSharp has a native serializer, but Newtonsoft is much more powerful, feature rich, and faster.
But, this is all for quality of life purposes. You can do all of this with the .NET framework in C# if you really wanted to.