If I’m not mistaken, the total amount of landings are already displayed.
Correction: The number if online flights can’t be seen from inside the app. To see them, you’d need to use a third party app like Live Flight or Map Flight which can be used to track your flights!
For example, I’m grade 5 with 3,021 flights but 1,824 landings. This is because I’ve spawned in the wrong aircraft / livery which counts as an online flight. Another reason for this is that I have done patterns at a training time but not done a touch and go which doesn’t count as a landing.