Turning On Secure Boot

I Upgraded to Win 11 when it was first available. I turned on TPM 2.0 to install it. Everything has been working OK. I just realized that "secure boot" was never turned on after installing Win 11.

Should it be on? If I do turn it on, would I still be able to do a clean install of Win 11 if I need to sometime in the future? Or would I have to turn it off again?

Thanks