My crop sensor is also able to use Canon’s full frame lenses. I don’t think Sony or Nikon do that.
The sony E-mount works for both APS-C and Full-frame. You can even mount an APS-C lens onto a full-frame, but you are down to 10-12mpx on the a7, I think.
If you rock bigger hands, you may want to go for a slightly bigger body for comfort.
My a6100 grip is serviceable with my medium hands. Some fancier a6x00 cameras use the newer and bigger battery, which improves the grip size.
I also have an a5100 and the grip is way too small, but you can hold it like a waist-level TLR camera and it's okay. It's missing a viewfinder, which is absolutely terrible. It's my e-mount backup camera that came as a lens cap for a lens I bought.
For reference, I use my a6100 with a 70-350mm or with the 18-135mm. I sometimes slap on the sigma 30mm for low-light.
I'm happy with it, and I think even a a6000 would have been perfect for me (the a6100 is my starter camera from 3 years ago).
Their flag is extra wide