IMac only loads in OS X utility mode (recovery mode)

Thanks for those details, MrE2021,

With that being the case, the iMac predates the existence of the App Store. What this means is that once the hard drive is erased, the iMac no longer has access to the internet recovery or means to access the App Store. You will need either the original discs that came with it, a separately purchased physical copy like the Snow Leopard 10.6 install discs, or an external bootable drive created using a different Mac with these steps: How to create a bootable installer for macOS

Take care!

Hello MrE2021,

We understand that you're trying to restore the iMac that you inherited. So long as the model came originally with Lion or above, it should be able to reinstall using internet recovery. If it predates Lion, then you would need physical install media like the discs it came with.

To confirm, you've gone through these steps to erase the drive and try to reinstall? Erase and reinstall macOS

Thanks

Understood MrE2021,

Do you know the model and year of your iMac? Here's how to find it: Identify your iMac model

Cheers!