Should I put sand in bottom of fire pit?

Gnee Garden

No. It may seem surprising, but your fire pit will work just as effectively with or without base holes.
Base holes do allow a little more airflow and so offer a faster burn, but that also means you will burn through wood faster.
Base holes also mean messy ash spills through the bottom of the fire pit.

iron fire pit table

camping vintage corten steel fire pit

black wood burning fire pit