Should I re-enable secure boot after installing linux alongside windows?

Mint boots fine with secure boot on in most cases, it uses a signed loader for exactly this. Just switch it back on and see. Worst case it refuses to start Linux, you go back into the firmware settings and turn it off again, nothing breaks. The usual catches: if you installed the Nvidia driver or anything else that builds its own kernel module, you'll get a blue MOK screen on the next boot asking you to enroll a key. Pick Enroll MOK and type the password you set during the driver install. And some laptops (Lenovo especially) have a separate setting to allow third-party certificates, that one has to be on as well.