It would appear its not possible, since Mincecraft launches out of the "launcher" and is not visible to the Screen Time settings to control.
https://bugs.mojang.com/browse/MCL-14705?page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel&showAll=true
Another user offers this advice:
Workaround with AppleScript:
YOU NEED TO GIVE MINECRAFT PERMISSION TO CONTROL SYSTEM EVENTS AND ACCESSIBILITY PERMISSIONS FOR THIS TO WORK. (It should request System Events permissions, but you may have to manually grant accessibility permission.)
You also need to enable "keep in dock" for the Minecraft launcher if It is not enabled already.
- Save the text file called "minetime.txt
" with no extension and make it executable - set the java executable to the text file you make executable.