Samsung is currently rolling out an update that allows the Galaxy Z Fold 3 and Galaxy Z Flip 3 to support an eSIM along with Dual SIM, and Dual Standby (DSDS). The eSIM technology is very convenient as all you need to do is download the SIM card information onto your device.
The recent firmware builds are labelled F926USQU1DVEE for the T-Mobile Galaxy Z Fold3 and F711USQU2DVEE for the T-Mobile Galaxy Z Flip3, while for the unlocked Galaxy Z Fold 3 and Z Flip 3 variants they are F926U1UEU1DVEE and F711U1UEU2DVEE.
This update will roll out gradually. So be expecting it on your device soon. Additionally, this new update will also introduce new camera features from the Samsung Galaxy S22 lineup into the Galaxy Foldable devices. The security patches of June come along with this update too.