I'd leave well enough alone. Secure boot/CSM has introduced more issues with Windows 10 and lack of driver support than anything else. With CSM enabled and legacy options available, you have the best of all worlds, you can use older stuff, older software or newer and still be supported. Switching to uefi only and secure boot throws all that support out the window, so if you do have an older card, or use 16bit drivers or have a need to run anything not upgraded and certified for Win10 Creators Edition or newer use, you'll have issues.
https://www.techrepublic.com/article/microsofts-new-hardwarefirmware-security-standards-promise-highly-secure-windows-10-devices/
You'll also need to have the entire list of other stuff too, miss just 1 and you'll still get that warning whether secure boot is enabled or not. It's all a decision by Microsoft saying that to have a secure pc you need this, which means dumping any older games, tossing any older software or hardware that doesn't meet some pencil pushers recommended settings.
Of course if you have questionable surfing habits or frequent the tabloid news sites or celebrity must see sites etc, then no amount of 'secure boot', TPM, 8Gb of ram necessity will mean you 'still' have a secure pc.