What does Blackmagic eGPU do

I’m looking to buy a new apple laptop. I love apple and I don’t want any other kind of computers like Microsoft or something. The problem is I also want to be able to play high end games like battlefield 1 or ark survival evolved, apple computers by them selfs can’t play the games so I’m wondering if I get the Blackmagic eGPU can I play any game on the laptop.