After updating my iPhone 8, I am not able to use WIFI or Bluetooth

Perform a Forced Restart on the phone. Follow the instructions very carefully, as this is a bit tricky. You may need to repeat this several times.

Force restart iPhone - Apple Support

There are only 2 possible results when you perform a Forced Restart:

1) The phone returns to normal operation

Or, if the issues remain......

2) There is a hardware problem with the phone that will need attention at the Apple Store (make an appointment) or take the phone to an authorized Apple Service shop.

You can find a list of authorized service shops in your area using the link just below:

Find Locations

Need some clarification on what "disabled" really means.

What do you see if you tap Settings > Wi-Fi?

Is Wi-Fi turned On?

Is Wi-Fi turned Off?

Is Wi-Fi greyed out?

What do you see if you tap Settings > Bluetooth?

Same questions for Bluetooth.

Hi Fl0cva,

Try following the steps in the following support article: If your iPhone or iPad won't connect to a Wi-Fi network - Apple Support

If none of those steps help, try connecting to a Wi-Fi network in a different location. If your device can connect, you need to get help with your Wi-Fi network. If your device can't connect to any Wi-Fi networks, contact Apple.

Turn Off Low Power Mode for the battery.

Wi-Fi is turned Off. Can you turn it On?

Same for Bluetooth.