My experience has been that once the drive is encrypted you can go into Settings -> Privacy & security -> Drive encryption and turn it off. Only took a few minutes to decrypt and it will stay that way until you turn the feature back on. It's trivial to flip back and forth between the two states.
In my case I recently purchased a new Lenovo IdeaPad laptop that came with Win11. I've had the laptop for about a week and I've done quite a few Win11 clean installs because I like to tinker. Anyhow, to answer your question, if i DISABLE SECURE BOOT in the bios Win11 will not encrypt the drive...