Hello,
The Related Products is basically a WooCommerce end feature that comes from their side and the Theme doesn’t influence its functionality.
According to WooCommerce, Related Products is a section on some templates that pulls products from your store that share the same tags or categories as the current product.
These products cannot be specified in the admin, but can be influenced by grouping similar products in the same category or by using the same tags.
You can read more about them here: https://woocommerce.com/document/related-products-up-sells-and-cross-sells/#section-3
Although, if you are using the Theme’s Layout Builder to create Custom Layout for the Single Product page and in that you are using the Products (grid or carousel) theme element > then in that you can specifically select Categories or tags for the Products appearing and can also Exclude some if you want: https://snipboard.io/hXK0ng.jpg
Hope this helps !
Best Regards.