True alt should always be very, very close to indicated altitude in normal ops (below transition alt), assuming your altimeter setting is correct. That's how we avoid obstacles and comply with chart and ATC altitude requirements.

Temp, and to a lesser degree humidity, affect density altitude much much more than they affect indicated altitude. Those two factors can be considered negligible for indicated altitude. Indicated alt is all about air pressure.

Density altitude should equal indicated alt at standard temp for that elevation, with correct altimeter setting.