There are two ways they design 'em. My RV kind of has both.
NORMALLY slide outs only move with engine OFF, there is an interlock that prevents moving them when engine is running.> Many reasons for this.
IT is assumed when you do your rear view mirror check prior to taking it out of park you will notice the slides out and shut down and bring them in.
HOWEVER: on some rigs it may be the slides wired to the chassis battery and since they are major power suckerS (Turned a 25 amp fuse into a flash bulb) the engine on those models needs to be on.
Jacks (leveling type) Normally are wired to the chassis battery and DO need the engine running. Reason same as slides. major power suckers.