Can i use aux cable with raspberry pi 3 or 4 for audio output?

[Burngate]

I'm not sure what you mean by "Aux cable", but if you mean audio only, 3-pole, tip-ring-sleeve, or similar, then it won't be a problem.

Yes, it will short-circuit the video output, but it's been designed to handle that.
Sadly, the details of the video output aren't available on the cut-down schematic, but they did think about that "what-if?" when they designed it.

[drgeoff]

I'm not sure what you mean by "Aux cable", but if you mean audio only, 3-pole, tip-ring-sleeve, or similar, then it won't be a problem.

Yes, it will short-circuit the video output, but it's been designed to handle that.
Sadly, the details of the video output aren't available on the cut-down schematic, but they did think about that "what-if?" when they designed it.

It was stated somewhere by someone representing RPT or RPF that the composite video output stage of the SoC is a current source and has no issue with that contact of the 3.5 mm jack being short-circuited to ground.