How do I fix Wi-Fi, Bluetooth, and AirDrop not working on my iPhone 8?

if it was me then I would

try

restarting the ios device Force restart iPhone - Apple Support and check if it resolved it if it did not

then I would try Restore your iPhone, iPad, or iPod to factory settings - Apple Support - Apple Support if that did not resolve it then I would

contact apple about repair Contact - Official Apple Support

Have you tried to force restart the iPhone to see if the issues persist?

1.    Press and quickly release the volume up button.

2.    Press and quickly release the volume down button.

3.    Press and hold the side button.

4.    When the Apple logo appears, release the side button.

If that does not fix it then it probably needs repair.

iphone 8 us now declared Vintage. Chances are it can't be repaired.