First of all, please make sure the graphics card which you use support AMD FreeSync.
Next, please get to AMD website and see the FreeSync monitors support list to choose your monitor.
--> https://www.amd.com/en/products/freesync-monitors
Here we use our VA5505RF41 graphics card with AOPEN 24HC1QR monitor.
After AMD driver installed, you can find the Radeon FreeSync option in the AMD Radeon settings.