Passcode locked iPhone 4S iOS 7

4S is obsolete. Even if you could fix the passcode issues, very few apps would run on the ancient iOS version on the phone.

If you forgot your iPhone passcode - Apple Support

Even if you could erase the phone to reset the passcode, you don't know the Apple ID and Apple ID password that was used to originally set up the phone, correct?

Your best bet by far....return the phone for a refund.

Never purchase a used phone unless the product powers on to the "hello" screen.

You bought a useless brick you can never use. I hope it didn't cost much. See if you can get your money back, but if you can't, recycle it responsibly.

Read this --> The All Too Common SAD Reality of Buying … - Apple Community

Resetting the Passcode is simple when connected to a computer.

If you forgot your iPhone passcode, use your Mac or PC to reset it - Apple Support

If you are met with a prompt asking for the Apple ID and Password, you will not be able to reset the device. Apple used to have a tool that would allow anyone check for Activation Lock using the IMEI number, but they not longer support this. You will find that a website that claims it can will not be able to produce accurate results.

How can I accurately check iCloud status … - Apple Community

You have the instructions to try to remove the passcode lock on the phone.