Developer-Dude Are you switching from iOS or Android? If switching from iOS, be sure to deregister iMessage amd turn off FaceTime before switching. The easiest method is to transfer stuff over via a USB cable from phone to phone.
cupcake-alibi You can copy files from a USB drive or from cloud storage using the corresponding app. I don't know about transferring settings and apps besides the Seedvault backup system in GrapheneOS.