You could perhaps be more specific about what STM32 and board you are talking about.
Most of the DISCO boards lack CAN transceivers
You'd do better looking at NUCLEO boards as they expose more of the pins so you could add a CAN transceiver
Several of the EVAL boards have CAN bus transceivers
Several of the STM32H7 DISCO/DK boards have FDCAN support
https://www.st.com/en/evaluation-tools/stm32h750b-dk.html
