My personal learning style generally involves learning in layers, and I would imagine a high-level overview of TLS 1.2 would be good since it provides some frame of reference before jumping into TLS 1.3, which from what I understand is an evolution of TLS 1.2 to provide better security. I seem to recall quite a bit of discussion during the development in regards to making TLS 1.3 look similar to TLS 1.2 for the sake of dealing with middleboxes.

If someone knows of a high-level document about 1.3 that goes through the handshake process and differences with 1.2, that would be a great reference to have!