Architecture decides organic performance for a retailer more than content does. Three layers are needed and most stores build two. Category pages for what the store sells, brand pages for who it stocks, and the intersection of the two, which is where the buying queries live. Those intersection pages need to be crawlable URLs with an editorial introduction, the range laid out, and internal links to the models people actually compare. Attribute layers underneath, such as size, colour or specification, should be built only where genuine demand exists rather than generated for every combination.
The content problem is that suppliers hand the same description to every retailer who stocks the line. A page carrying only that text is competing with dozens of identical pages, and none of them have a reason to win. Rewriting the descriptions for the products that matter, adding your own photography, publishing the questions your support team gets, and showing genuine review content is what separates one retailer's page from another's. It cannot be done for a hundred thousand products, so it gets prioritized by revenue and by search demand.
The technical work is faceted navigation, pagination and the lifecycle of a product page. Filters multiply URLs quickly and need rules that decide which combinations are indexable. Discontinued products should point at their replacement rather than disappearing, since those pages often carry links and rankings that took years to build.