I'd be down for this. In fact, there's times where this would've been useful.
What OP is suggesting is something to turn off hitboxes automatically when you're switching to your pickaxe (or other stuff) so you can actually mine instead of hitting players, then turn it back on when you switch to a selected item (swords, hands, etc).
Currently on Hypixel, any hitbox larger than 0.3 will cause the all chests with armorstands inside of them to be untouchable, since you're hitting the armor stand instead. Super annoying in the lobby when you want to open a chest you got, but it makes Blitz and Sky Clash impossible to play since you can't open any chests.
That, and there's been multiple scenarios where I'm trying to mine something and one of my teammates walks just barely behind me or right next to me. They'll think it's fine to get my attention, but what they don't know is Hitboxes causes me to hit them even though they're not in front of me.
This is terrible if you manage to get stuck in a 1x1 hole with somebody else, hitboxes makes it virtually impossible to mine the blocks above you 'cause no matter how high you jump, you're always hitting them.
Outside of just those few instances, this isn't needed and might actually flag an anticheat since your hitboxes are being inconsistent. I haven't seen anyone get banned for changing their hitboxes on and off, but one of the devs here said that different hitboxes per entity would set off alarms or make it detectable, so I figure that'd be the case here.
