Can I Recover Photos from a Reset Phone?

I recently traded in my old phone at T-Mobile, and the employee said he backed up everything. However, when I got my new phone, I found out all my photos from the last two years are gone, including precious pictures of my late cat and my new kitten. I'm feeling really upset about this, especially since there seems to be some confusion about the devices. My parents were told it was an Android phone, but when we got home, it turned out to be a Google Pixel, which is technically an Android but has a different interface. Is there any way I can recover my lost photos? Maybe from the phone's hard drive?