To control sleep mode behavior during remote sessions, you can set keys in the /Library/Preferences/com.vmware.horizon.plist file on the Mac client.

Key Description
kPreventSystemSleepWhenBeingSessions If the value is true, Horizon Client prevents the system from going to sleep if remote sessions are connected. If the value is false, Horizon Client does not prevent the system from going to sleep. The default value is true.
kPreventSystemSleepBatteryPercentage If the battery status is Not Charging, and one or more remote sessions are connected, Horizon Client prevents the system from going to sleep if the remaining battery power percentage is not less than the value specified in this key. The default value is 50.

If no remote sessions are connected, the client sleeps according to the system settings.

This option works only when the kPreventSystemSleepWhenBeingSessions is true.