Well, cargo is a special case to begin with, under TCA rules. But even without going there, the TCA does provide for wet lease from the UK to the EU, however, only in very limited and special cases. So it is not something that can happen on an everyday level. The other way round there is no such caveat.
For air cargo the TCA provides the express possibility to have bilateral agreements between EU member states and the UK about fifth freedom rights on a reciprocal level. No such provision is given for other air transport operations.
But of course, both areas can dry lease without any restriction from each other area, so there might be D-registered aircraft flying with UK licensed crew within the UK, and G-registered aircraft with EU licensed crew in Germany for example. I have no idea how DHL UK currently operates, but it could be interesting how it works within the confines of the TCA.
The TCA provides no further freedoms apart from 3 to 5, and 5 only for air cargo.