@fais3000 you can use a child theme or a template plugin to do so.
BBcode for NodeBB?
I tried nodebb-plugin-bbcode-to-markdown and nodebb-plugin-bbcodes but they did not work.
Is there anything working?
@vstoykov are you looking for something with a WYSIWYG editor, or what? A simple plugin with BBcode parsing is easy. One that also adds a new composer like nodebb-plugin-bbcodes is more difficult.
There is nodebb-plugin-redactor which you can use if what you're looking for a WYSIWYG editor.