Hi there,
Thanks for writing in! You can add your scripts like below on your Child Theme’s functions.php
function my_custom_head_output() { ?>
<script type="text/javascript">
// Add your custom scripts here
</script>
<?php }
add_action( 'wp_head', 'my_custom_head_output' );
If you wish to achieve this through plugin, then you can try this : https://wordpress.org/plugins/header-and-footer-scripts/
Cheers!