Tira here, from Shopify Support.
Thanks for your question. I appreciate that you've looked into this. Would you be able to share a link to the thread that you found this solution in, so that the community could take a look?
This is expected behaviour on some themes like Brooklyn. I recommend using a different theme to enable the image zoom feature on mobile. Here are some themes that you might find helpful:
The paid themes are created by third-party developers. For any questions, please reach out to the third-party developer directly by clicking on the "Support" link on the theme's page. You can also check out our help doc on where to get support for your theme, here.
Another option is to hire a Shopify Expert. Shopify Experts specialize in making customizations on your store. Check out a list of our Shopify Experts here: Shopify Experts Marketplace.
Let me know if this helps!