Depending on the industry / region in which you work, they will have regulatory obligations to protect sensitive data such as PII and PHI. From a business perspective they are trying to remove liability and decrease of obvious attack vectors they have limited control over. From an individual perspective, they are implementing controls that protect the privacy rights of their customers. As a security professional, it’s good to see. Personally I would always prefer to keep work and personal items separate to reduce the chance that I’m the cause of a breach.

It depends on the registration profile they require. If they have you register it as a company owned phone vs a BYOD device.

BYOD registration creates a separate partition on your phones hard drive for the apps installed via the company portal. They cannot see all apps on the device, or any web traffic, sms, phone calls etc. they cannot lock the device or wipe the device in its entirety, only the apps on the company partition.

So in short, it depends on how the IT / Security department setup the device registration, and the registration process will notify you of the access level and allow you to accept / deny.