how do I open my phone if I forgot my code to get

Forgotten lock screen passcode?

There is an Apple article that explains what to do if you have forgotten an iPhone or iPad passcode. Click on the following link: If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support

If that option is not available, you will need to use a computer. See: If you forgot your iPhone passcode - Apple Support

or forgotten Apple ID/iCloud password?

See: If you forgot your Apple ID password - Apple Support