More reserved for insiders
Earlier this year, Mojang rolled out a new program for Xbox Insiders on the Windows 10 platform that allowed users to try out new graphical improvements for Minecraft.
Framed around NVIDIA RTX boosts, the update added ray tracing and a suite of visual upgrades to specific worlds built around them; to great success. It looks like all of that testing is done (it took about eight months) because Mojang just made RTX upgrades available to everyone. All you need to do is own the Windows 10 version of Minecraft and you're good to go.
From there, search the main store for free RTX Tiers so you can actually experience the update in all its glory. The names usually contain "RTX", so they're easy to find, but here are a few options if you want specificity: "Colosseum RTX" and "Dungeon Bash RTX".
Once you are there, if RTX mode is not enabled, just press “; » key to toggle it. You can do it at will, over and over again! And if your friends are in the same world via cross-play and don't have RTX capabilities (whether on PC or another platform), they'll just see the "normal" visual style. It's pretty awesome.
Even if you don't play Minecraft, head over to the official site and check out the handy RTX/non-RTX sliders on each of the images. It's funny!