Thanks @bentolor for guiding me into right direction: arendst/Tasmota#8984 (comment)
Example for automatically disabling Power after 10minutes or 600seconds:
Rule1 ON Power1#state=1 DO RuleTimer1 600 ENDON ON Rules#Timer=1 DO Power1 Off ENDON
Rule1 1
Each line needs to be execute separatly in Tasmota console. Tested on SonOff BasicR2 with Tasmota 10.1.0 and it's working perfectly fine.