Prakriti
Hi, I'm a Mindflayer, but don't let that worry you
If you're a DM, and you think a player's character is under-performing, then just add class-specific magic items to the treasure.
Is the Ranger not doing enough damage? Drop a Longbow +2 into the treasure. Or create a new item: Longbow of the Wilds. +2 enhancement bonus. 3 charges. Casting Hunter's Mark costs 1 charge. Charges replenish at dawn the next day. Can only be wielded by a Ranger.
Is the Ranger's pet wolf too weak? Create a new magic item: Collar of Animal Fortitude. This item gives an animal companion an extra 4 hit points per Ranger level. If the companion drops to 0 hit points, it rolls death saving throws just like any other character.
And so on.
Is the Ranger not doing enough damage? Drop a Longbow +2 into the treasure. Or create a new item: Longbow of the Wilds. +2 enhancement bonus. 3 charges. Casting Hunter's Mark costs 1 charge. Charges replenish at dawn the next day. Can only be wielded by a Ranger.
Is the Ranger's pet wolf too weak? Create a new magic item: Collar of Animal Fortitude. This item gives an animal companion an extra 4 hit points per Ranger level. If the companion drops to 0 hit points, it rolls death saving throws just like any other character.
And so on.