The community members are discussing the right way to add a max character limit to an excerpt and then display "..." at the end. The suggestions include handling it from the CMS, using CSS to visually shorten the text with an ellipsis, or doing it on the backend. There is no explicitly marked answer in the comments.
you could use css for this just to shorten visually using ellipsis, methods in expressions for now are not supported, another option is to do this on the backend