But if you find that when dating, you are writing off entire groups of people, like people of colour, fat people, disabled people or trans people, then it's worth considering how societal prejudices may have shaped your attractions.
That may be true, but the way to consider it is by thinking and maybe discussing, not experimentally sleeping with people you're not attracted to, just to see if it changes your mind. It's okay to reach the conclusion that yes, my preferences have been shaped by a whole pile of social conditioning from the day I was born, but I can live with that. I am not going to sleep with people I'm not attracted to. I don't get to sleep with all the people I am attracted to, for a variety of different reasons. It's okay to say no for any reason. Sex should only ever happen when it's mutually desired. No one is actually entitled to have sex, whatever men think.