I forgot my 4 digit passcode

There is no option to recover it. See the following for the available options:

If your iPhone has iOS 15.2 or later installed, see: How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support

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

I forgot my 4 digit passcode , how do I recover it?

Unfortunately, you don't. But, if you have a recent backup of your iPhone, you can restore the backup after you reset the iPhone.

Details here: If you forgot your iPhone passcode - Apple SupportOfficial Apple Support › en-us

If you had iOS 15.2 or higher installed, then use this link: How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support