From the Trello.
Ability to add in the option to change the size of the text in chat message bubbles on channels. This would be something that could be set from the chat settings cogwheel (pictured below), and give the user some options in increasing or decreasing the size of the text used.
Would help in accessibility for those of poor sight, as well as allow others who want to ‘fit more’ messages on the page to do so.