To be fair, I haven't dealt with a 32 bit system in a good while now. I cannot recall if there is anything more to it than downloading the OS installer and performing the clean install.
Windows 7 is out of support and a very quick search across MS site didn't seem to point to an available (official) download of that OS.
I did note when looking up driver support that the CPU supposedly works with W8 and W10. Considering that, for now, you can continue to run W10 without activation it would likely be worth a try to get an 8GB USB, go to Microsoft site and download the official USB installer and give it a go.
A point of consideration: If you don't have your original recovery disks or OS disk available (and license key) this could swerve toward a non-optimal situation. Your key "should" be tied to the hardware and/or your MS account. So far as I know MS hasn't completely killed the W7 to W10 upgrade, but to be fair I never tried it on a 32 bit base license.
If it were me and I was going to "give this a go" without the confidence it was going to work out right, I would remove the OS disk (C drive) as it is and attempt this upgrade on a new and empty storage device. (new/used HDD or SSD)
2nd point of consideration is that this CPU is not strong, never was, and likely not to notice any difference if not even a penalty to performance. There may also be other limitations involved in such as "adding more RAM" from motherboard hardware limitations. You didn't list yours, so be sure to check into that as well.