Explain to me how this website work and how can I make similar

Job ID: 36692659

Budget: $10 – $30 USD

This website uses and app that the shoppers can generate create custom products like print on demand.
https://wowfulfillment-preview.myshopify.com/products/personalize-your-canva-shoes

The part im interested in to understand is the mockup generator (Previews generated). When the user uploads an image and places it in a place, the previews get generated and the placement of the image in the canvas matches the position in the previews. The previews are in different angles and but the position of the image is same and renders properly.
I checked the network of the website and it seems that it Posts a json request to the server that responds back with the rendered image, but what could be in the backend that renders the images like that, that is what I need to know and what do I need to achieve same.
Related categories: XML Software Architecture JSON SVG