I'm Richard - CRO Expert at PageFly Landing Page Builder. Welcome to Shopify Community!
Regarding your concern, you could refer to UploadKit app, I know this app currently is not free of charge, however, starting at $9.95/month with 2,000 uploads per month is worth a consideration. Besides that, UploadKit Fields element has been integrated with PageFly allowing users to easily use via drag-and-drop system. You can check this manual for more details.
Hope my answer will be helpful to you.
Best of luck!