Here's an idea. Old slash fiction porn often listed pairings at the top as content labels.
Woman/girl
F/f
Kirk/Spock
This is a visual version of that using emoji's.
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On Windows 10, click a text-field, press (WIN + .) then type a word to search for that emoji. Press enter to replace the text with the emoji. Press ESC to close the emoji window.
Being just pictures, the meaning is less obvious until you hover over them to reveal their emoji text labels, but you can cram more of these labels inside the teeny-tiny content label warnings box.