You can run a few ultra settings at 4K no issue but move ‘texture resolution’ to high, this makes a big difference even on a 4080s. Try 150/200 LOD. Use the settings guideline for which ones you can just click ultra and ones you may have to compromise on. Off-Screen Pre-caching is one you want to click on ultra first along with ground Terrain Vector Data, these make the most overall impact on the ‘world’ you see and how snappy viewing to the sides will be. You can turn everything else to high and still looks good with just those two. Turn off AI traffic (use Real Time traffic) and use free apps like FSLTL and/or GAMod. AI traffic crushes the CPU mainthread and it’s poor anyway, lots of GA aircraft flying at 200’AGL and doing nonsensical stuff.
Remember your system is higher spec than this one. If you’re 1440P you should be rock and roll, 4K can get crunchy with too many settings. I assume you’re at 4K if you’re struggling with settings with a 4070s
Settings are a bit different based on flying bush/backcountry or over major metropolitan areas, usually when you have your settings in a happy place, you can just push out your LODs for bush and bring them back a little for major airports/city areas.
If you’re using the developer FPS tool, look for a more green/yellow stream with the occasional single red fetching line, you don’t want red in the stream.
Remember that ‘high’ settings are default for MSFS ‘high end’ systems. Everyone feels compelled to go ultra everything. I think texture resolution on ultra may overwork the GPU trying to process all the random different scaled textures for things you can’t even see a difference with.
ETA Oh, and make sure you’ve synced your clock in windows, it’s a thing…