Yep, you can do either, although they work in different ways.

You can import a PDF through file > import Model, then select the PDF you want to use as a floor plan. It will be imported through the model importer, so you can set scale there. It's imported as a model, so you get the proper wireframe view, and it's viewable in 3D as any 3D object is. Manual reference here: https://www.capture.se/Ma...document-format-.pdf

If you only have a PNG, then you could use a tool to convert a PNG to an SVG (vector format) then to a pdf, potentially, or a different workflow that would allow you to trace the floorplan within the png and export that in a usable format. Otherwise you can add it as a material onto a plane. This will only be viewable in a live view, as textures aren't rendered in a wireframe or plot view. So it's not the easiest way to build 3D geometry.