I don’t know my old passcode and if I rest with my new one will it lock my phone

If you reset it that will restore your phone to factory settings.

If your device has iOS 15.2 or later installed, you can reset it without a computer; check out this link→How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support. Otherwise you will need a computer:

See this Apple support link→If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support

Or watch this companion video ⬇️

After restoring the phone using one of the methods above you can restore your most recent backup.

If I reset will it lock my phone

No it won't. It will erase the phone and restore it to factory default settings..... so you can set it up again with a new passcode.

If you forgot your iPhone passcode - Apple Support

If you don't have a computer, try......How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support

Might be a good idea to write down the new passcode......even if you are sure that you will never forget it.

If you have a current backup of the phone, you can use that during the new setup, so the phone will look just like it did before you forgot the passcode.