Can I plug the USB-C cords directly into 240v without using the Apple power adapters while charging devices in Europe?

You can plug the USB-C cords into any USB-C port for charging yes. 240v applies to AC power outlets not USB-C ports. All USB-C ports should provide the same 5v DC regardless of country as it's a universal standard.

You can also plug them into any European charger brick with a USB-C port, those will also convert the 240AC to the required 5v DC.

You can also use plug adapters for your US chargers. US charges are universal and can handle any AC voltage from 110 to 240v.

All Apple iPad USB power adapters are designed for use with power sources rated to provide 100V AC to 240V AC at 50Hz to 60Hz. Apple iPad USB power adapters also comply with the IEC/UL 60950-1 and IEC/UL 62368-1 standards for use with power sources rated to provide 115V AC at 400Hz (typically found onboard commercial airlines).

While your Power Adapter will be fully usable when travelling internationally, you may require a simple pin-adapter to allow the Power Adapter to be used with AC power outlets in different countries. For example, a US flat 2-pin connector will require an adapter for the standard European round 2-pin socket - or UK 3-pin square socket. Travel adapters are readily available.