You can add to the cart with Line Item Properties, not just a quantity and id:
'First name': 'Caroline'
First of all, thank you for taking the time to answer. Unfortunately, I do not understand your answer. Where should I add your code and is it necessary to customise it?
Please send me url of the page and then I can send you exact code to add in your them. Or I can do that for you as well.
My Url: https://luxusly.com/collections/sonnenbrillen/products/die-unzerstorbaren-fruhlings-und-sommer-sneak...
I hope you don´t mind that my page is on German.
You need to first get the varient id then pass that id to to js while adding products into cart. If you know js and liquid you can easily do that. Thanks