Bluetooth & Wi-Fi issue on my iPhone 12 with iOS 18.6

Try a Forced Restart, which is the first thing that a technician will do if you take the phone in for service, so this might save you a trip to the repair shop.

Force restart iPhone - Apple Support

If there is no improvement after a few tries, this indicates that there is hardware problem with the iPhone that will require attention at the Apple Store / Genius Bar or at an authorized Apple service shop.

You can find a list of authorized service shops in your area using this link:

Find Locations

If you cannot turn on Bluetooth or wi-fi, it is more than likely a hardware fault. The iPhone's chip that controls Bluetooth also controls wi-fi, so when they both fail, it is usually a chip failure. Make a Genius Bar appointment at the nearest Apple Store and have the hardware examined. Apple will explain your options. Genius Bar Reservation and Apple Support Options - Apple

It is normal for Bluetooth and Wifi to be scanning for available devices/networks. Are you saying you can't connect to a Wifi network on your iPhone. The more details you provide the easier it will be to help you.