Can MAC OS Ventura encrypt USD Flash any drives?

You may be selecting the volume instead of the device by mistake. Try these steps:

1. In the menu bar at the top of your screen, click View > Show All Devices
2. Hold Control and click your flash drive in the list of devices (click the device, not the underlying volumes)
3. Choose the "Erase" option
4. Set the "Scheme" field to "GUID Partition Map"
5. Set the "Format" field to one of the encrypted file formats

You should have assigned the Best Answer to timdiffernet's post rather than yours so he would get the credit for solving the problem.