I've got a Sony A7R IV and Sony A7 III, which I will be upgrading to a Sony A7 IV (released in December 2021). I've been very impressed with their capabilities and have had many opportunities to improve my photography and capture great images.
As for a lens, I’d definitely say a telephoto lens. Having a longer lens enables me to get really close up and capture animal portraits without having to be that close to them and change their natural behavior. The length of your lens is critical in enabling you to capture your subject without changing its behavior too much. They'll know you’re there and run away from you, and you won't get an accurate image. My favorite lens is the Sony FE 24-70mm f/2.8 G Master.