Code added to shopify store

I am looking for a Shopify expert that is able to add some code to my website.

I would like to add a Line item property code. This will enable to to not have finger size as a variant leaving me more options to keep within the 100 variant limit on shopify.

This is what I would like: https://community.shopify.com/c/Shopify-Design/Product-pages-Get-customization-information-for-products/m-p/616525

I have attempted this myself but the theme I am using is different so will need someone that has experience.

More details on options required can be provided.

Thanks