passcode

Yes, you will lose all of your data that is not synced to iCloud (I mean synced, not backed up - they are not the same). There is no way around this. See-->If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support

To sync data to iCloud before wiping your phone go to Settings/{your name}/iCloud. Any switches that are turned on will sync the related data to iCloud. You can repeat this step after setting up the phone as New to get back any data synced this way.

You will get back the data for the apps that you synced to iCloud. Not all 3rd party apps sync to iCloud, so you will not get data for those apps back from iCloud.

However, many apps today sync data to the app provider's servers, so those data will also come back. The only data you will lose is apps that only keep local copies of data on your phone, and that don't sync it to either iCloud or to the app provider's servers.

You have to reset the phone and then set it up as new.