Do you mean those fancy signature at the end of each post? I think some forum infrastructure has that. The closest you can get in Discourse is to save a template and load it for every post you make.
https://discuss.eroscripts.com/t/how-to-use-reusable-templates/77112
I’d say probably don’t include one in all of your posts though. It’s not something common to Discourse forums and it gets annoying at times.
