Let me pick between A, C and D but adjust the font size to my liking.

This is coming from a visually impaired guy constantly using screen magnification: The ability to adjust font sizes is an insane help as we can now match how far we scroll our magnifier versus how much information we can guess from a glance without.

On Element on my Android phone, I have a much bigger font size, so I can skim messages for words by their optic. If I am interested, I can zoom in with the screen magnifier and read. Since the font is bigger, I don't have to zoom in far to read it well, but still have enough density that I have to move the view a little.

I wouldn't neccessarily call this an "accessibility killer feature", but definitively something I would absolutely want.

Thanks for reading!