iPhone 6 Wi-Fi settings is blank/Photos app keeps crashing when scrolling up or clicking a certain picture

So I got this iPhone 6 from my uncle. It’s pretty old and it’s only 16GB so it’s not that much. He told me that he couldn’t view his photos and that it was very slow. So he told me to reset the phone and now the phone is still acting the same. I can’t access the Wi-Fi settings page because when I click it, it’s just blank. Bluetooth and cellular data is okay but that’s the problem why I can’t update it to iOs 12.4. Also, apps kept crashing. The photos app crashed when I scroll up and reach a picture or when I click on a picture that’s pretty far up. I really wanna figure this out. My friend told me to get iTunes and update my phone there but is there any other way to be able to fix my issues without updating the phone?? Thanks!!