Is it possible to connect a file with data about the database to all site files at once?

Question

PHP

There is a db-config.php file, it contains data for connecting to the database, password, name, etc., is it possible to make it so that not to enter a large request like connect to the database in each file, do what we need, disconnect from the database, but connect and that's it, but disconnect the connection after a timeout or after closing the tab with the site.