You need to make the distincition between frame size and video file compression and wrapper format.
Premiere Elements 12 has both project preset and export opportunity to deal with import export of a file with 4K pixel dimensions (3840 x 2160). But, whether or not the codecs and wrapper formats involved will be supported by Premiere Elements 12 is not known with any certainty. From what I have read, the 4K from that camera is classed AVCHD progressive, MOV, or MP4 formats.
Generalizing, a AVCHD.mp4 or AVCHD.mov file should be supported by Premiere Elements. I am not sure at this point what Panasonic has done with what is describing as MOV and MP4 formats which it offers in addition to the AVCHD progressive format. In the absence of a file extension for AVCHD progressive and lack of definition for codec and wrapper formats for the MOV and MP4 choices, there are no guarantees.
Do you have Premiere Elements 12 and Panasonic camera at this time? Your best answer will come from testing the specific footage from the camera in Premiere Elements 12. And, if you do not have Premiere Elements 12, you could download and install the free 30 day tryout for this purpose.
Please update us on your progress. Please do not hesitate to ask if any questions or to ask for clarification.