Mac storage basics · Erasing, encryption and selling a Mac
Is my Apple silicon Mac's storage encrypted even without FileVault?
Short answer: The storage is always hardware-encrypted, but without FileVault it unlocks at startup with no password. FileVault ties unlocking to your login password.
The internal storage on Apple silicon Macs is always encrypted by the hardware. FileVault adds the important part for you: it ties unlocking to your login password, so someone with the Mac but without your password can't read your data. Without FileVault, the data unlocks at startup without a password.
Turning FileVault on is quick on these Macs and has no noticeable performance cost. See FileVault.