The OneUI 3.0 update comes with build version F900FXXU4DUA1. The update is currently being rolled out Globally via an OTA (Over-the-air) update. The update is carrying the latest January 2021 security patch update as well.
As we mentioned it above the update brings the latest security patch update which was released by Google in January 2021 Security. Most of the security vulnerabilities have been addressed. It also brings some bug fixes which were available in the previous build. Thus, you should download and install the update to your Samsung Galaxy Fold which will come as an OTA update to your phone.
You can manually check for the update from Settings > Software update >Download updates manually. If there is no update showing on your device, then wait for few days for the update to come to your device as it is being released phase-wise manner or you can manually flash the full firmware using Odin Flash Tool.
