Create a Bootable USB Stick for an old 2008 iMac

Hey!

I have an old iMac from 2008 with Windows 7 installed over Boot Camp. Now I want to reinstall OS X because somehow the OS X Partition got deleted. I also tried to open the Recovery partition, but it wouldn't work because there isn't one on older iMac's. I also lost my DVD with OS X sooo im kind of screwed... Now I want to create a Bootable USB Stick to later plug into my iMac to then install OS X again. My Question is, how do I do that? I watched tons of videos, but they don't seem to help. How can I create a Bootable OS X USB Stick in Disk Utility on my MacBook Pro from 2018 with macOS Monterey?

Otero