Hi @websul
Thank you for the question.
Unfortunately ACF does not offer this functionality out of the box. You can however checkout this plugin that offers a similar functionality https://wordpress.org/plugins/acf-multisite-sync/
You can also make use of the native ACF export functionality to manually add the fields to the multisite. you only need to follow these steps:
1) Network Activate Advanced Custom Fields
2) Create Field Groups on the Main Site through the Custom Fields Menu.
3) Use Custom Fields –> Export, select all field groups, Export to PHP
4) Paste the PHP into your (child) theme’s functions.php
5) Go back and trash the fields from the main site so there aren’t duplicates.
