Apple Business Manager

For an unboxed device, there is absolutely no way to check if it's enrolled into an ABM account of some organization. The best way is to purchase from Apple, or its authorized reseller or carrier since there's always a way out of the management (if any) via them.

If you're buying new, buy through an Authorized Reseller and you won't have an issue. I would not trust a device that I could not touch from someone who isn't one.

Make them wipe it in front of you and see if you can get past the activation lock screen in the setup process.