Is this cat ringworm?

From the photo you uploaded, the cat’s symptoms do not look like those caused by ringworm. Besides ringworm, allergic reactions, external irritation and bacterial infection can also cause red skin in cats.

To tell whether the cat is infected with ringworm, you can shine a Wood’s lamp on the affected area; if green fluorescence appears, it indicates ringworm infection. If ringworm is ruled out, it is recommended to take the cat to a veterinary hospital for further diagnosis and treatment.