If you're happy to pay for it, the best solution is to install Magic Zoom Plus. The user experience is more invigorating than the default zoom tool and Magic Zoom Plus has a powerful full-screen view on click.
The app also supports switching images with product variants.
It's the highest rated product image app on Shopify. We're the creators. Our team provides free support to configure the app if it doesn't work immediately on your store.
and what if I'm not happy to pay for it? it seems that JQuery Zoom is already in the Brooklyn theme..
Probably you ve also found this famous zoom tutorial: https://easycodeguide.com/add-zooming-function-shopify-theme.html
but I'm stuck with pasting script (point 5). if I do it in theme.liquid and then /head/ section - it doesn't work :/ I would make a guess that it is colliding with the scrolling function a few lines above:
... so if anyone knows - speak up please!