Hide-login is optional and Advanced. Most sites should leave wp-login.php visible and keep lockouts plus two-factor on.

If you still want it: in WP-Admin open Bedrock Shield, Settings, then Customize, Login Protection. Turn on Hide the login URL and set a slug. Save. Sign out and open that new URL once before you close the old tab. If you lock yourself out, add define( 'BEDROCK_SHIELD_DISABLE_HIDE_LOGIN', true ); to wp-config.php.

Test on one site first. You never change DNS for this. Turn on two-factor first if you have not. If the whole site is blocked, see Locked out of the site.