First off - this is no guarantee, but it should help.
The secret sauce to finding you iPhone after you’ve looked in the obvious places is Apples trusty ‘Find My’ App. Previously called find my iPhone, it will also track your Apple Watch, iPad, Mac’s and even AirPods. To do this is need location access and many people don’t give it enough access to be able to do the best job it can.
Privacy is a huge deal, and this is understandable, but should the worst happen you really want to track down your device as quickly and easily as possible. I have spent 20 mins rooting through my car, only to then trace my AirPods to being back at home on my desk - this tip may help recover your device and calm you down.
Send Last Location
The secret is allowing your device to update its location when it is used. This is stored by Apple and no one else - but it’s understandable if you don’t want to do this.
When you open the ‘Find my’ app for the first time you will be prompted to allow this. If you’ve missed it or now want to turn it on head to Settings > Tap Your Name at the top > Find My > Find My Device > and toggle on Send Last Location.
There is also an option to allow offline location. This will allow a location even if the device hasn’t got a data connection by pinging other Apple devices around it. This is similar to how Tile works and is linked to the much rumour Apple version.
You could also consider sharing your location with friends of family members so they can also track down devices for you, however this has its own pitfalls!