How to make WordPress using local CSS/Fonts/Scripts only

There is a plugin Airplane Mode that tweaks good chunk of network–related things core does.

I am not entirely sure which kinds of external resources you mean. If you import site and its media into local development installation then most of it will be local already.

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