And they lie shamelessly. Sometimes it does good and sometimes it does bad. Let me explain...
When you take a selfie - the portrait at the end of your arm - you are asking a telephone to see you at your best. It will generally not do so, as it is too close to you ( in a physical sense ) to avoid unpleasant optical distortions. It is often said about portraits painted in oils that there is always something wrong about the mouth - the mobile phone selfie will have something wrong with the nose.
You can reduce this somewhat by removing the mobile phone to a greater distance with a longer focal length lens. While the ideal distance - about half a mile - is hard to achieve in crowded tourist locations, you can attach a selfie stick to the device and shoot yourself in the head from about 1.1 metres. Socially distance yourself from you. Voltaire would approve.
You'll still have to contend with the fact that you look like
you and not what you'd like to look like. Your nose will be fine, but your mouth will now, like the oil painting, be no oil painting. Smile or frown? Or try for a neutral expression? You're actually better off gurning for the camera than trying to look dignified - in most cases you look sillier the more serious you try. If all else fails take 15 shots and photoshop the best eye from one with the best mouth from the other.
Is there a better way? Yes:
a. If you want to remember the fact that you stood in front of the Eiffel tower, buy a postcard of the damned thing - or a book. Or go over with a hammer and a cold chisel and take off a rivet. With any luck it will be a master rivet and the whole edifice will collapse.
If you want to impress people with the facftthat you were in Paris...save your time. The locals didn't want you there and your friends don't care.
b. If you want to remember the people you were with, use your real camera or your mobile phone to take pictures of them - with you operating it while looking through the viewfinder from a proper distance. If you get a good one, change places and have them do the same for you. Two good portraits are better than one bad selfie.
c. If you must use a phone, use one with a mini tripod and a phone holder that will allow it to be further away than the end of your arm. Better still, use one of these.
Ring up Central and ask the lady there to take your picture. Peer down the mouthpiece until she tells you she's got it. It'll be in sepia but you'll love it.