In Shopify you're limited to 100 variants with little to no customization fields (think needing monograms/names etc). Infinite Options is a Shopify add on app that allows you to bypass that limit and collect ALL the information you need.
I’ve made a tutorial video on Infinite Options which shows you how to make options, creating option sets, creating multiple options within an option set, conditional logic, and pricing upcharges. I’ve also included little tidbits of info I’ve learned from using the app for several years.