hi, i have a 1000+g bp that is a mice feeder, it's in off feed now for almost 3 months, is it ok if i switch it to rat by offering a rat pup every 2 weeks?
yes, though you could probably just feed a small rat.

will it starve itself to death if not givin what it's used to eat?(mice) thanks in advance
no it will not starve itself to death. A healthy adult ball python can go well over 6 months without food.