Recipe calls for garlic powder and all I have is garlic salt
Garlic salt is typically 3 parts salt to 1 part garlic powder. It's mostly salt.

That means if you use 3x the amount, you'll end up with roughly the same amount of garlic powder, but also a lot of salt.

Are you able to reduce salt elsewhere in the recipe? If not, I would just leave it out. Generally you can substitute garlic powder for garlic salt (just add salt) but not the other way around.