Internal linking

I have a large e-commerce catalog with over 100+ collections and 35,000+ SKUs. I need help optimizing internal links for this catalog. What's the most cost-effective approach for bulk optimization, and how much would it cost?

Please provide a solution and pricing and timeframe without asking about my budget.

here is my website:

www.art-and-see.com

Highly appreciated.

Have a good afternoon.