What to require
Look for conditional templates, archive control, single-post templates, header/footer building, dynamic data support and WooCommerce coverage where needed.
Divi
Divi’s Theme Builder can create headers, footers and templates for posts, products, categories and other site areas using its visual builder.
Alternatives
Elementor, Bricks, Beaver Themer and block-theme approaches can all cover parts of this job. Compare the exact template conditions and dynamic fields your site needs.
Decision
Do not buy a theme builder until you list the templates you will actually maintain. The right tool should reduce repetition, not create another layer of complexity.