In some cases, yes. The UPC is a new untested court and the agreement allows the possibility in some cases (for a limited period of 7 years) for patent owners to remove their patents out of the jurisdiction of the UPC.
However, opting out of the UPC’s jurisdiction will only be possible if the patent in question is a classical (non-unitary) patent – if your patent is a unitary patent only the UPC will have jurisdiction over it.
The default status for all patents, even classical European patents, is that it is within the jurisdiction of the UPC – to bring a classical European patent out of the UPC jurisdiction and back within the jurisdiction of national courts, the owner has to register its opt out of the patent at the UPC registry and pay a fee of €80. Unless the patent opt-out is subsequently withdrawn (also requiring a fee) the patent will be remain outside the jurisdiction of the UPC for the remainder of its term. Note that a European patent cannot be opted out if an action concerning that patent has already commenced at the UPC.
When any action is commenced at the UPC a check is made to ensure that it is not opted out.