There are some cases in which a new user will only post questions. Those will not be in the proper format. If we try to change the contents to the proper coding format and then click the update button, it will show "Edits must be at least 6 characters; is there something else to improve in this post?" message. So what shall I do for this?
It is very uncommon that there is nothing else to fix in a post without proper formatting. Salutations/Signatures normally appear in such posts, as do "Help me please", some variation on "Thanks in Advance", and/or lower case "i". Plus there is usually spelling & grammar mistakes or spaces before punctuation (if there is any punctuation at all). The point is most often there is something to fix in order to get over the 6 character limit.
Some new users will post only code with out the coding format
If there is nothing in the post except code, then leave a comment for the OP and explain what to edit and what they need to add. Might even be helpful to link to markdown help page. Without any explanation in the question body, it will likely be downvoted, closed, and deleted - so a comment would be better for the OP in the long run.