I have a very early vintage Ikonta Super C 6x9 530/2 with a 10.5cm Tessar f/4.5 SN1538091 in a Compur Shutter SN12225524, Zeiss Ikon body SN Y 55030, which may match yours. The lens takes 37mm push on filters and hoods. The Zeiss filters and hoods are sized to enable some stacking. However, my camera will not close with any filter in place on the lens. I found the filters readily available on eBay several years ago (ca. 2010 is about when I accumulated them), and in surprisingly good condition.
The camera is a joy to use and behold, and the Tessar produces its classic magic, surprisingly nicely in color as well as monochrome despite its lack of coating. I consider the camera one of my most fortunate finds over my too many years of over-accumulating gear. It was my first and remains my favorite folder (even over a Bessa RF with f/3.5 Heliar, nice images, but nowhere near as pleasant a shooter).
Larry