If you want to add a front end form to login to your website you can do this using the following snippet of code on your template file. You can control if you want the user to be redirected to the back end or a different page with this. This awesome snippet of code was found here:https://ahmadawais.com/create-front-end-login-page-wordpress/
true,
//'redirect' => home_url( '/wp-admin/' ),
'form_id' => 'loginform',
'label_username' => __( 'Username' ),
'label_password' => __( 'Password' ),
'label_remember' => __( 'Remember Me' ),
'label_log_in' => __( 'Log In' ),
'id_username' => 'user_login',
'id_password' => 'user_pass',
'id_remember' => 'rememberme',
'id_submit' => 'wp-submit',
'remember' => true,
'value_username' => NULL,
'value_remember' => true
);
// Calling the login form.
wp_login_form( $args );
endif;
?>