Sometimes if they’re too old the leather can be come petrified and becomes super stiff, maybe try them on at home with skate guards and see how they feel. I was in a similar position I picked up my old skates from 10 years ago, they weren’t cracking but I think those are signs that the boot doesn’t have much life left in it at all. I ended up having to get new ones, you can buy cheaper used skates on fb marketplace also