To allow users to see a zoomed version of your images in HD when hovering in the view product modal, or full page embed, simply enable the Image Zoom switch.
For hosted stores, this can be found in Sales Channels -> Hosted Store and then in the View Product Popup menu in the left-hand sidebar, look for the Image Zoom switch. Enable it, then save your store and the change will be reflected immediately
For embedded stores, this can be found in Sales Channels -> Existing Website and then in the View Product Popup menu in the left-hand sidebar, look for the Image Zoom switch. Once enabled, you'll need to copy the newly generated embed code again and paste it where you'd like to display your products.
Please note, options are specific to each embed code, so if you have multiple embed codes throughout your site, you'll need to replace each one you'd like the changes to apply to