Will resetting my iPhone delete all of my data?

An iPhone reset will clear all local photos, all local files, local mail, and all other locally-stored on-my-iPhone data.

The reset will not clear iCloud Photos, iCloud Drive files, iCloud Contacts, iCloud mail, or other hosted data.

Yes, your phone will be wiped. If you choose to set it up again, any data that is restored will depend on if you have a backup, or if any of the data is currently being stored in iCloud. It is possible to store Contacts, Messages, and Photos in iCloud that would be restored without a backup, but not sure if you are using iCloud to store any of that data. Data stored in iCloud is not affected by a Factory Reset of any device.

There are many possible reset procedures.

Settings > General > Transfer or Reset iPhone > Reset yields the following: