Click the following link for some Intel HD 620 game benchmarks. The only game you mentioned that is there is CSGO which it should have no problems playing at 1080p resolution. Using ultra settings is still playable, but average FPS is in the low 40's.
https://www.notebookcheck.net/Intel-HD-Graphics-620.172256.0.html
Below are some game benchmarks for the Intel Iris Plus Graphics 650. CSGO is not benchmarked, but the more demanding Overwatch is, and the Iris 650 performs better in that game compared to the HD 620. That means it will perform better in CSGO than the HD 620.
https://www.notebookcheck.net/Intel-Iris-Plus-Graphics-650.190370.0.html
Here is Skyrim being played on Dell Inspiron 15-5567 with a core i3-7100u and Intel HD 620 at default settings and 1366x768. I do not think he stated it, but he is using a video capture device to record gameplay, not software. That means you are seeing the actual performance.
https://www.youtube.com/watch?v=xqhkIHDc0n4
With some tweaks to the SkyrimPref.ini you should get good performance results at 1600x900 or even 1080p. I tweaked Skyrim on my friend's laptop with a 4th generation i5-4200u and Intel HD 4400. I got it to run at 1600x900 with average over 40 FPS. So with a 7th gen i5 / i7 and Intel HD 620 an average of over 50 FPS at 1600x900 should definitely be possible with the right tweaks.