How do I activate the new (2024) in app / on screen translation?

Late 2024, maybe December, maybe November, I received an update that allowed me to translate any text in any app. I can no longer work out how to activate it. It was something like swiping up from the bottom of the screen, or maybe long pressing the text to translate. It did not need to take a screenshot to translate. What is this feature called and how do you activate it?