Hello!
Our campaigns have 90% tolerance for duplicate content so this means if the page source code is at least 90% similar, it will be flagged.
Canonicals will only work if all pages that are truly identical each point to the same canonical URL
So if you have something like www.domain.com/productA/ as the primary URL for a single product
All 3 URLs below need to point to "www.domain.com/productA/" as the canonical
www.domain.com/productA/color=blue
www.domain.com/productA/category/tag
www.domain.com/productA/page1
For another product www.domain/productB/
These will always report as a duplicate of productA if there isn't enough unique content to prevent them from being too similar due to the layout/template making up the majority of the source code.
For pages that are completely targeting separate products, those cannot be ignored so it will help to add more unique content to those pages to prevent getting flagged.
Here is a great article on how you can address duplicates for a site like yours: www.goinflow.com/duplicate-content-ecommerce-seo/
Hope this helps!