What’s the best way to maximize trade-in value

Hello, I have one iPhone 16e, 2 iPhone 15s, one iPhone 14, and one iPhone 13, all on a family plan with T-Mobile. Our current plan is: Experience More 2.0. I’ve seen $930 for the 16, $730 for the 15s/14, and so little for the 13 that upgrading it is a lost cause. I’ve seen so many people talk about Costco and Apple trade-ins, what would be the best strategy to maximize trade in value for these phones? Would waiting for Black Friday be better? Thanks everyone.