My iPhones are out of storage

Please do not confuse your device's internal storage with iCloud storage. The former cannot be increased, the latter can.

See this article about that matter:--> What's the difference between device storage and iCloud storage? - Apple Support, and check the two storages status.

Regards

Giulio

Questions for you:

1. Which model is the new iPhone?
2. What is the total storage capacity of the old iPhone and the new iPhone?
3. What is the exact storage error message that you are getting on the old iPhone and the new iPhone?
4. Do you use iCloud for storage?

Axel F.