Guess it depends in which airline. In my last interview i was interviewed by a 22 year FO and 30 something cabin manager, applying as a captain. The rules still state that tattoos shouldn‘t be visible, but wearing a long sleeved shirt is fine, and anything that is covered by that. I have met quite a few tattoed pilots, including those wearing them pretty much on the full alrea covered by the usual long sleeved uniform. But then, i guess that some areas of the world are not as conservative as others.
I was once working in an airline that was in the process of changing its uniform and appearance manual to allow visible tattoos everywhere except on the face, following a marketing campaign with a heavily tattoed girl. The airline in question is now gone, but not really as a result of that campaign (which was, at least in its intended market, rather well received) but rather continued bad management over more than 10 year.