In order to take advantage of this particular Windows 11 feature, you’ll need to have a monitor with a high refresh rate connected to your PC — otherwise, your display simply won’t be able to make use of the setting. If you do have a screen that can handle more than the industry standard of 60Hz, you’re good to go.
First, you’ll want to verify what your monitor’s refresh rate actually is (unless you already know it). You can check this by opening the Start menu and selecting Settings > System. You’ll find the refresh rate displayed in Hz near your screen resolution. After that, open Settings and select System > Display > Advanced Display. From there you’ll see a drop-down menu, which you can open to find several refresh rate options including — if you have a compatible display — a Dynamic option, which you should select to utilize the DRR feature.
Setting the refresh rate to Dynamic won’t necessarily improve the visuals on-screen, but you will probably start to notice that things seem to be running more smoothly. Look at how transitions between various Windows interface elements move and react, for example. Also, keep an eye out for frame rate drops, and be prepared to adjust your dynamic refresh rate settings again if things appear a bit too choppy for your liking.
Source: https://www.slashgear.com/990763/the-hidden-windows-11-display-setting-that-you-should-know/