How to replace an SSD?

I've got a new internal SSD on the way to double my storage (1TB -> 2TB) and i'm excited for the extra storage, but curious on replacing it.

It's more than just physically, my main worry is file transfer. Most tutorials I see just cover physical, some say how to set up a new drive, others say "just transfer the files over" without mentioning OS. It's all very confusing and inconclusive for someone who has only ever replaced my RAM. I just want to copy everything on my new SSD, wipe my old one, and then resell it.