So I have sizes of products as actually products and linked it through meta fields by product ID to kind of create a variant selector look. I DONT NOT WANT TO CREATE VARIANTS WITH IN PRODUCT.
I want the collection to use a default product to be able to link the size handles as a dropdown selection.
Product page, make it product size is a requirement.
This is doable. You seems to know the things you have to do. Yes you have to add the products connected to a certain product using metafield. Since, you are doing it this way, there will be multiple edits you have to do depending on the theme you are using. I would suggest to have a developer do this for you.
You can use the code below as reference to edit the product page.
{% for variant in product.metafields.custom.variant.value %}
{{ variant.title }}
{% endfor %}