Are there any tools or software which can be used in elementary ? If so, do they support CYMK format other than RGB ?
GIMP, Krita, Darktable, and Inkscape are not made specifically for elementary OS or created with the HIG of elementary OS in mind, but they will get the job done and are available in AppCenter.
elementary OS has it's own photo manager called Photos which also allows for very basic picture manipulation tasks.
GIMP is a well known image manipulation program and a popular alternative to Photoshop. Although it doesn't have built-in CMYK support, the Separate+ plugin can allow you to convert from RGB to CMYK.
To install GIMP, head to AppCenter. A newer version can also be installed from Flathub.
This is not necessarily a complete solution for CMYK, though:
CMYK data is interpreted and processed only within separate plug-in. From a GIMP's viewpoint, it is not recognized that CMYK data is processed.
Hence your mileage may vary.
I use Inkscape.
It support CYMK, RGB and HSL.
It's a vector graphics editor, so may not be what you want. Install it from AppCenter, or get a newer version from Flathub.
I recommend Darktable. It is available in AppCenter, or a newer version is available on Flathub.