Nice monitor! Not only nice but should provide incredible graphics for a long time. I am using a monitor very similar to yours and I have fairly consistent 50-60 FPS except at crowded airports.
As for settings, stepping up to a 4k monitor means using new settings. First, use a new DisplayPort cable, not. HDMI. Second, check the manufacture’s support website for a specific Windows 10/11 driver. Windows usually only uses a generic monitor driver.
Initially don’t try using different rendering settings or configuring HDR until your monitor is adjusted to what performs best for you. For most of the NVIDIA settings, use the 3D setting to use the application settings. This avoids setting conflicts between MSFS and NVIDIA. Depending on the NVIDIA filters you are using, there shouldn’t be any FPS drop unless you use SHARPEN+.
Send me a message if you would like additional info on the settings to use for MSFS.