How can I get back into my phone through iCloud if I am locked out because I forgot my password?

If you forgot the passcode on your iPhone, or your iPhone is disabled or unavailable -

Click on the link for instructions on how to reset your passcode without a computer if you have iOS 15.2 or higher.

If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support

Click on the link for instructions on how to reset your passcode using a computer.

If you forgot your iPhone passcode - Apple Support

How can I get back into my phone through iCloud if I am locked out because I forgot my password?

You can't.

Apple does not keep your passcode for you. If you have forgotten the passcode, you have to reset / erase the phone and then set it up again with a new passcode using instructions that have already been provide in the previous reply above.

It might be a good idea to write down the new passcode......even if you feel that you will never forget it.