There are a few different ways:

• VM: doesn't give you the "real" experience. Often feels sluggish.
• Installation via package manager: really clutters and messes up your system. There are many dependencies, and then you'll have 5 different file managers for example.
• Ventoy: the second best option, or the best, if you just wanna take a look at each. If you really want to try the DE for a few days, it isn't suited of course.
• Fedora Atomic (immutable variants like Silverblue): there's a project called uBlue, that provides images for all DEs. You can install the vanilla Silverblue, and then rebase to each according image. Your custom installed programs and personal data stay intact, but everything else gets swapped out cleanly. Each rebase would take ~5 minutes and one reboot, but it feels like you reinstalled your OS and changed the flavor.