It has taken Sony a while, but it has confirmed that VRR will be available via HDMI 2.1 on the PlayStation 5. Variable Refresh Rate will be available system-wide, so existing games will not need updating. Sony's VRR announcement comes as the company has released a new update for the PS4 and the PS5.
https://www.notebookcheck.net/PlayStation-5-to-finally-receive-HDMI-2-1-VRR-support-as-Sony-releases-updates-for-the-PS4-and-PS5.609628.0.html