“Tattoos themselves are morally neutral, but the choice of tattoo is what can make it immoral (sacreligious imagery, upside down crosses, images of devils, etc)
Think of it as putting on a piece of clothing. What you choose to wear can be immoral, provocative, and irreligious“
https://catholicgentleman.net/2014/06/a-marked-man-should-catholics-get-tattoos/