I have built an iOS game with Unity. I uploaded it to the App Store (with bitcode enabled). The IPA is about 200 mb.
On iTunes Connect, it shows my build size to be about 30mb for each device (which I was very happy to see).
But when I added the build to TestFlight, I notice that while downloading via TestFlight, it shows the size to be 170mb. Quite contrary to this question (TestFlight showing my app size is 4 times less than the actual size) the size of my app on TestFlight is many times the actual supposed sizes shown on iTunes Connect.
Also, iTunes Connect says:
TestFlight variants differ from store variants and have smaller sizes.
App size increase in Testflight is common, and is completely normal
It includes Bitcode and code to analyse crashes. Once the app in in the app store it'll come back to normal size.
You might also notice that for various screen sizes the size varies dramatically.
Edit After comments:
If you are worried about the size of your App Store file, you can check using below steps