GDPR does not care about cookies too much, but the few sentences in the regulation means a lot to you, as a website owner.
Since it can be used to precise identification of a particular person, then yes. And it's true, that using the Unique ID in combination with IP address you can supposedly identify the particular person.
That's simple. If you want to store and use personal data of the visitors of your website, first you need to have their valid opt-in consent. Usual Cookie Consents widgets widely used on a thousands of websites do not comply with GDPR because they don't use the requested opt-in consent and do not offer the user the right choice. According to GDPR, user has to have a clear ability to choose whether he wants to allow you storing his personal data or not. If not - you as a website owner - should not deny him using the website. That's why usual cookie consent widgets are out of the play.