Can one product have a different page design from the rest?

Yes. Product page designs are templates, and each product can use its own.

1. Go to Settings → Appearance → Product Templates. Under System templates, click Clone on one, or click Add Templates. Build your design and it is saved under My templates.
2. Open the product. In the Organization card, set Product Template to your new design. Click Design this layout ↗ to jump into the builder for it.
3. Save the product.

Products without their own choice use the template marked Active on the Product Templates page. Click Activate on a template to make it the store default. Templates can also be exported and imported as JSON.