I understand that you want to swipe product images and increase the image size on your Debut theme when someone views your store on mobile. Is that correct?
If so, Debut is a free-theme from Shopify, which means we support certain customization options from our design team, you can find more details on our Shopify Design Policy page. I looked into this with our team and the ability to swipe product images on mobile would be outside our scope of support, as it means the entire product page would need to be rebuilt.
I recommend looking into third-party apps from our App Store for product images. One app in particular, Product Image Gallery & Zoom by Gravity Software can swipe product images on a mobile device. To view a list of similar apps, you can take a look at our App Store: product image apps. As these apps are developed by third-party developers, I recommend reaching out to the developers for any questions or comments. You can do this by using the information listed under the “Support” section of the app’s page.
To enlarge your photos when clicked, you can check out our advanced tutorial on adding a lightbox to product images. Please note that as this is an advanced tutorial, it would be outside our scope of support.
If you want to explore other options, I recommend looking into hiring a Shopify Expert. A Shopify Expert can code customizations into your store to enhance it. Check out our list of Shopify Experts here: Experts Marketplace for custom visual elements.