Thing that I know happens, from personal experience: you can put a giant modal alert, and write in blinking, all caps, 60pt bright-red font that you will do something unless the user presses a button, then draw a bright red arrow to the button. Users will still complain that they weren’t informed.
Users are lazy and dumb, and the most ideological users are often the laziest and/or the dumbest, because they have an agenda. They will go out of their way not to give you the benefit of the doubt (”why was the font not 80pt? Clearly, you’re trying to hide something from users on high resolution screens!”)
If your goal is to eliminate user complaints about this, justified or not, then just stop intrusive data collection entirely. Then you don't need to bother with obtaining consent.
Users are lazy and dumb, and the most ideological users are often the laziest and/or the dumbest, because they have an agenda. They will go out of their way not to give you the benefit of the doubt (”why was the font not 80pt? Clearly, you’re trying to hide something from users on high resolution screens!”)
It never ends.