Enthusiast

I have just converted from a Canon DSLR to the Sony A7 iii. I got a Sony 24 - 105 f4 lens to start. For my next lens I’m considering either the Sony 16 - 35 f2.8 or the 70 - 200 f4. Any recommendations on which I should get first? Also I hear that Sony bodies excel for low light shots. Why would a f2.8 lens be worthwhile?