How to check if an Apple device is managed by a corporate account

Navigate to Settings > General > VPN & Device Management.

If you don't see anything, your device is not managed.

Could you share with us what makes you think the device is managed?

Did you buy it used?

Did you allow your employer to add a management profile to it or add it to an MDM?

If the answer to those is no, then you device is not "managed".

That said, if you have set up a corporate (Exchange) email account on the device, the administrators have the ability to enforce policies on the device and to remotely erase the company owned data from it.

What says Microsoft?

EXACTLY what are you seeing?