Moving to a new phone is straightforward, because your wallet is not tied to any single device, it is restored from your recovery phrase.
Install Celia on the new device and choose I already have a wallet, then carefully enter your 12-word recovery phrase. Your crypto and your cash profile come back once the wallet is restored.
The one thing to be absolutely clear about: if you no longer have your recovery phrase, your self-custody crypto cannot be recovered by anyone, including Celia. This is exactly why we ask you to store those 12 words somewhere safe from the very beginning.