The Mini is designed to run 24/7 so there's no feature to turn it on/off by schedule. However, you can schedule your content to play at specific days and times by using the scheduling tool in the Windows version of XOGO Manager: https://www.xogo.io/digitalsignageblog/2019/12/2/xogo-advanced-scheduling-feature
Remote Reboot:
You can also reboot your Mini remotely by clicking on your player in the Players section then going to Advanced at the bottom of the screen.
Power Management Solution:
If you want to schedule your Mini, TV and/or other items to turn on and off automatically - for instance to conserve electricity - you may want to consider an internet-connected power strip like this one that will turn your devices off at certain times of day: https://www.ubnt.com/mfi/mpower/