There are two different settings that are relevant here, but they do different things.
The first enables TLS 1.3 for use, and is under the TLS 1.3 section of the Edge Certificates tab of the Cloudflare SSL/TLS app. Without this enabled only TLS 1.0, 1.1 and 1.2 are available.
The second is the minimum TLS version which is on the same tab, and this can be used to disable the older versions of TLS that are generally not needed any more.
I would recommend that TLS 1.3 is enabled, but that the minimum TLS version is set to 1.2.
I still see a sizeable amount of traffic using 1.2, so cannot see a general purpose domain being able to set the minimum to 1.3 yet, that is probably a few years away.
Once you have enabled 1.3, you can monitor your application and your traffic to make a decision on when and if it is safe to disable 1.2.