Alchemical Arrow

You use your alchemists' supplies to tinker with a ranged weapon, piece of ammunition, or weapon with the thrown property. Choose one of the following damage types: acid, fire, or poison.

Make a ranged weapon attack with that item. On a hit the target takes damage as normal, but the damage of that attack becomes magical if it wasnt already, and deals damage of the type you chose.

At Higher Levels.  When you reach 5th level the target takes an extra 1d8 damage of the chosen type. The additional damage increases by 1d8 at 11th level (2d8), and 17th level (3d8).