How to enqueue multiple style sheets into my child theme in wordpress (oceanwp)

You had the right idea, but made an unfortunate typo: . './custom/navbar.css'.

Removing the additional fullstop should correct the URL, otherwise you were succesfully enqueing a stylesheet, the code just enqueued the wrong URL due to the typo

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)