Breastmilk to formula help

Willow • mother-sister-wife-daughter 🌸

I'm planning on weaning my little on to formula. I'm not producing what I should be and things are just becoming stressful for work. However I know nothing about formula. Is it okay to give it to him cold? I would pump some breastmilk and put it in the fridge to help cool him down and he'll his teeth... but is it okay to do that with formula?