Fallon Stone@jentaub got some clarification on this matter from @Curator . Not a strict rule, but best practices across the fediverse and exhibits a distinctive kindness. Sorry about the confusion 
dabneyl@FallonStone @jentaub @Curator How do we do the content warnings? I want to be respectful and I often post about politics.
Patrick@dabneyl @FallonStone @jentaub @Curator Dabney, I think it might vary by instance, but for me, I see an icon that isan exclamation mark in a coversation bubble above my keyboard. Click that to get a "warning bar" in which you type the textof the CW. Then type your post in the normal location.
@StackaTurtles so helpful. Thank you. I went in to where I publish and saw for this server they have a CW at the bottom I can click - if this helps any other newbies!