Yes. It’s not like all the EU laws the UK had adopted before Brexit suddenly went out the window overnight.
Also, I'm not sure about this "immediately enforceable" part - I recall some cases where member states delayed implementing EU laws for years, sometimes ending up being sued to European Court of Justice.
AFAIK it works pretty much the same in all countries and only depends on whether it's an EU regulation[0] or an EU directive[1].
[0]: https://en.wikipedia.org/wiki/Regulation_(European_Union)
[1]: https://en.wikipedia.org/wiki/Directive_(European_Union)
As the GDPR is a regulation, it directly applied to member states.
When the UK left the EU they made a paralled law
> The GDPR has been incorporated into UK data protection law as the UK GDPR see: https://ico.org.uk/for-organisations/dp-at-the-end-of-the-tr...