The first screen deals with the typical monitor settings.
You may adjust the Field of View between 85% and 115%. Note that the default is 100%. So these are not the degrees we are used to, but relative to whatever default they chose. I found the 100% setting to be sufficient, and I usually dial up my FOV a bit.
The FPS limit defaults to "off", but can be set anywhere between 30 and 90 FPS—no idea why the maximum is 90 and not higher.
Assassin's Creed Valhalla supports "windowed," "fullscreen," and "borderless."
Non-16:9 resolutions are supported, too, like our 16:10 2560x1600, Ultra-wide.
There is no artificial FPS limits, V-Sync can be disabled. There's a third option, "V-Sync Adaptive", which enables V-Sync automatically on high-refresh rates, but disables it on lower FPS to avoid stuttering—nice idea.
On my system, the resolution scale defaulted to 70%—change this to 100% if the game feels blurry to you. This option will render the game at below native resolution before upscaling it. The HUD always stays at the native resolution. You may also run supersampling; the slider goes up to 200%—the minimum is 50%.
For graphics quality, there's "Low," "Medium," "High," "Very High," "Ultra High," and "Custom."
Adaptive Quality lets you select an FPS target (30, 45, or 60), and the game will automagically adjust the details settings to reach that level. Higher values would again be useful.
Anti-aliasing is only available in "low", "medium", or "high". No "off," and no details on the algorithms used.
Lots of other settings to fine-tune performance to your hardware