TOS tried to push the envelope on that but was limited by the censors and the special effects of the time. We saw characters whipped to the point of bleeding, tortured via various neural devices, beaten, sexually assaulted (by Kirk on a few occasions), electrocuted, chained up, struck with iron bars, placed in a vacuum chamber, burnt.
Then we had TNG with Chain of Command, with Picard being assimilated and Remmick's head exploding, DS9 with young Nog traumatised having his leg blow off amongst the more notable events of the war, VOY with Tuvok being tortured, Archer being tortured in ENT, everyone and their dog being tortured and even eaten in DSC.