Hi,
the OC mode as well as other modes are described in the device Reference manual in FTM chapter.
In OC mode the output is changed when the counter matches the value in the CnV register.
Also you can refer to AN5303 Features and Operation Modes of FlexTimer Module on S32K; https://www.nxp.com/docs/en/application-note/AN5303.pdf
BR, Petr