Prepare your PC after your backup is complete. Given that your iPhone is sluggish, a factory reset using iTunes is a preferable option for ensuring that everything goes well. You may use a Windows PC or a Mac computer as long as it's running on a recent operating system, if not the most recent. Also, make sure you have the most recent version of iTunes on your computer. When you've finished, Once you all have the requisites checked, proceed with these steps:
- On your PC, open iTunes.
- Use the USB or Lightning cable that comes with your iPhone 8 Plus to connect it to your computer.
- Follow the on-screen instructions to proceed if you are requested to enter your device passcode or to Trust This Computer.
- When your iPhone is detected, it will appear on iTunes. In iTunes, find and choose your iPhone.
- Then, browse to the Summary screen on iTunes.
- Restore [device] by clicking the Restore [device] button.
- Read the message prompt's information, then click the Restore button once more to confirm.
- Allow iTunes to wipe your device and install the most recent version of iOS on it.
The gadget will reboot automatically after restoring factory default settings. When it has completed booting up, set it up as new.
By now, everything should be in working order. If that's not the case, you'll have to consider an iOS restore.
