@Lola, I'm not entirely sure what you mean by
"complete function like a normal lens added to a camera with exchangeable lenses capability", but if you mean that you would like to have the ability to easily install
and remove a CPL filter on this Varifocal CCTV lens that is not designed for removable filters then you would need to add some threads to screw it into.
That wouldn't be all that hard to achieve. All you would need to do is glue a suitable threaded filter adapter onto the front bezel of the lens. There would be several options for how to go about this. For example you could install a 28mm to larger diameter adapter such as this 28-37mm step-up ring. An adapter that takes a much larger CPL which might be desirable to eliminate any possibility of vignetting. Many adapter sizes and options are available. Of course, the back side of these filter adapters are male threaded and that is the part that you would need to glue to the front of the lens. The 30mm CPL filter I glued to my varifocal lens has rear male threads that are just about 28mm in diameter and all I did was glue the threaded part of the filter to the front of the varifocal using UV cement. It was pretty easy and it fit nicely on the front bezel of the lens. If you want to you could even grind or sand down the male threads on an adapter to create a flat or flatter surface for gluing.
FYI, 28mm CPL filters are widely available. Any size CPL you purchase will have rear threads that are a couple of millimeters smaller than the diameter of the filter bezel itself as you can see in the third photo below.
Typical threaded step-up filter rings look like this with female threads for the filter you wish to install.
View attachment 39787
They come in a wide range of sizes to adapt different sized filters to different sized lens bezels.
View attachment 39788
As mentioned, the back of these adapters are male threaded and look like this.
View attachment 39789