I'm an old millennial AuDHD and I have to resist the urge to use bold and italics everywhere for different kinds of emphasis. I'd use even more variations when available (text size, colors).
When I was younger, I used to do the same in analog form with multi colored pens when taking notes.
I don't often bold comments, but i do like using italics and sometimes all caps to EMPHASIZE an important part. I guess the difference for me is whether it's something I get fired up over like bodily autonomy. I use caps to emphasize more than italics.
In a regular discussion or if I'm just overexplaining something, I stick to italics. (and if I feel something needs additional clarification, but also maybe the reader wants to skip because it's not really necessary, I'll use parenthesis to show where you can skip to)
Oh! Same. You cannot portray the nuances of speech easily through text. I often feel like my intentions may be misconstrued if I don't emphasize or elaborate, lol. I still have an array of colored pens for personal and close friend/family use!