How do i recover passcode on 8 plus without wiping out the data

I’m not sure it’s possible. However, here are some articles that may provide some help:

https://support.apple.com/en-us/HT204306

Contact Apple Support: https://support.apple.com/en-us/HT204306

If you forgot your passcode, you can restore the device If you forgot your iPhone passcode

The data will be lost. There is no way around that.