I use UTF-8 on all my pages, but some Swedish characters (å ä and ö) get messed up (just a square box with some letters in). My database is set to utf8_gener
I found "https://www.html.am/reference/html-special-characters.cfm" and by entering the characters code, I was able to imply whichever character I was looking for. No need to import a specific lib or anything.
Example: Swedish 'ä' = ä . So 'Stapelbäddsparken' = Stapelbäddsparken in HTML.
I hope this will be helpful.