First buying a small camera and then adding some extra size for the little finger. I'm sure there's some sense in this... Good thing is, I can trust my little finger to manage some time underneath the Z 7 and not feeling lost. BC is correct (except with Tino... ), don't talk about a battery grip if you cannot put a battery into the grip. EG stands for Extension Grip, it gives the 5th finger some parking space.
More seriously: This EG-P1 probably will be difficult in any shop to try out. If you use tripod heads with Arca clamps, you might want to look into a L-plate, as some of them are also coming with an extension. Like that one: https://www.smallrig.com/smallrig-l-bracket-for-nikon-z6-and-nikon-z7-camera-2258.html
They don't show Canon RP on their site, but I'm sure there's one or coming soon.
More seriously: This EG-P1 probably will be difficult in any shop to try out. If you use tripod heads with Arca clamps, you might want to look into a L-plate, as some of them are also coming with an extension. Like that one: https://www.smallrig.com/smallrig-l-bracket-for-nikon-z6-and-nikon-z7-camera-2258.html
They don't show Canon RP on their site, but I'm sure there's one or coming soon.