How do I clone a product? Is there any method yet for cloning existing products in Drupal Commerce 2?
Be careful with the https://www.drupal.org/project/entity_clone module. Because it may happen that you've made a ton of product clones and then decided to edit, let say, price of some variation on a clone or a "parent" product. The price will change everywhere. The same with deletion of variation. Moreover, the same with deletion of any of the clones or the "parent". All variations will be deleted everywhere. But that's not the end. If you try to delete any of variation-less clones you'd get fatal error. So, to delete this clone you need to save at least one variation.

That's because variations are entities which can be referenced by multiple products. Read more: https://www.drupal.org/project/commerce/issues/2941524

So, as I understand you need cloning for cutting off the time spent on variations creation, which is quite tedious work, I'd say. If so, you may try the Commerce Bulk module.