Secure Boot Off and back On

A computer with Windows 10. The BIOS shows ‘secure boot’ is on. Select secure boot and a message says: if turned off, Windows will be unable to boot.

That seems an unnecessary restriction but OK – IF it is the case that after saving the BIOS changes with secure boot turned off, I can later go back into the BIOS, turn secure boot back on, and the system will be back to normal. YES or NO?

Why? Certain bootable tools I’ve used for some years on other systems, such as a special purpose Linux system or a DOS troubleshooting system that can run multiple extended memory hardware tests, will not boot when secure boot is turned on.

Turning it off should not stop Windows from booting (does not with my 2 PC's). Worst case just turn it back on and the system will return to normal.

True that some systems will not boot with it turned on.

Turning secure boot off will not prevent Windows from booting, so long as you don't disable UEFI booting mode as well.

Secure boot just check if the OS you're booting is digitally signed. It's a security feature to avoid booting malware. On my computer Secure boot is off and Win 10 boots normally.
Old OS (like Win 7) or those on your boot able tools you've used for some years on other systems, such as a special purpose Linux system or a DOS troubleshooting system that can run multiple extended memory hardware tests, will not boot when secure boot is turned on because they are not digitally signed.