Cypress is presently evaluating adding the BLE 4.2 features to the Ez-serial firmware. We will update once we have done the evaluation.
Hello Kenji Takahashi-san,
The Ez-BLE modules that we are shipping at present supports BLE spec 4.2 features. Updating the Ez-serial firmware to BLE 5.1 in Ez-BLE modules is not possible because our Ez-BLE chip will have space issues (especially modules with 128 KB flash) and the chip does not support BLE 5.1 new feature.