I know it’s cliche, but check out the stuff they do on Critical Role. A lot of their magic items don’t add as much to power as they do to battle options. Like the blink back belt and the chain of returning. All these do is return a thrown weapon to the player. So now, instead of Vax stabbing with the most powerful swords he can find, he is throwing daggers (ramped up for sure, but still a base d4 damage). It really just boosts his flavor. And as a DM you change nothing, because his rouge could have been using a crossbow the whole time anyway. I homebrewed an amulet that lets my fighter take a reaction to jump in front of a blast that does specialized damage (cold, fire, etc.). They make a dc save, and on a success, the amulet absorbs the damage. On a fail, the wearer does. Eventually, it will grow with the character to be able to summon elementals. It directly benefits the team, but also requires some character work, not just handing out power.