My company just started requiring Microsoft Intune Company Portal app to use Teams and Outlook. From a friend in IT infosec at another company said the app can push apps, require certain settings, password requirements, or OSs, and can see a lot of stuff on your phone. I don't think this level of intrusion into my personal phone is warranted or ethical. Be warned. I'm just going to uninstall and suffer the internal political consequences.
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.