Hello @yawarabbas ,
They are using any product option apps to achieve that functionality. You can have something similar to this with the Inkybay - Product Personalizer app. This app has a ‘Product option’ feature where you can have a swatch display style as your color variants. The main product image will change according to the selected colors from the swatch. And you can also have the size sets.
This app also offers 21 days of free trial time. So you can explore and see if this will work for your business or not. I hope it helps.
Let me know if you want to check this demo product. Thank you
