The Usercentrics CMP does not impact cookies that were previously set. The CMP blocks technologies such as cookies and tags until the user chooses otherwise. Once  the user agrees, the respective technology can then set cookies, fire tracking pixels and use other tracking methods.
If a user changes his or her mind in the course of the session and opposes a technology, the CMP will block the technology from that point on. And in the case of a cookie it will automatically expire at the end of its lifespan.