Product Attributes Query

I am looking to create a product attribute that is highly variable rather than fixed. I.e. imagine if the options are not red, green or blue, but may be any hex color code.

From my understanding, the product attirubutes are normally selected from a pre-defined range of variables that you set. In this instance this won’t be effective, as there are an almost limitless range of options depending on the product.

Possibly a better example would be food products, where the amount of sugar the product contains could be almost anything.

How can I create an attribute where we can enter any text we like for this attribute when setting up a product?