Starfield may have enjoyed a relatively smooth launch by Bethesda standards, but those are some pretty low standards and this particular iteration of "like Oblivion but with guns" still has some notable omissions. At the top of the list: the absence of a field-of-view slider in the options menu.
Starfield guide: Our hub of advice
Starfield console commands: Every cheat you need
Starfield mods: Space is your sandbox
Starfield traits: The full list, with our top picks
Starfield companions: All your recruitable crew
Starfield romance options: Space dating
If you're one of the players frustrated by the fact Starfield is locked to an FOV of 70, forcing us to explore the galaxy with horse blinkers on, fortunately there is a fix. And no, you don't have to download a mod for it.
To change the FOV, first open up your Documents/My Games/Starfield directory. There should already be a StarfieldPrefs.ini file in there. You want to make a new text document in that folder, named StarfieldCustom.ini, and use Notepad to put the following lines in it:
[Camera]
fFPWorldFOV=xx
fTPWorldFOV=xx
Where xx is your desired FOV, whether 90 or 100 or 120. The first value is for the first-person view, the second for third-person. Unfortunately, there doesn't seem to be a way to change the player and weapon viewmodel to suit the new FOV. The higher you go the more likely it is you'll notice your hands and anything you're holding looks zoomed out. Though oddly, this won't kick in immediately on changing the FOV—only after the first time you go into a dialogue scene with an adjusted FOV will it affect your hands.
If you want to change the FOV for piloting your ship, add the following lines as well:
[FlightCamera]
fFlightCameraFOV=xx
That'll tweak the first-person view in your cabin, but there doesn't seem to be a way to change the third-person spaceship FOV, more's the pity.
Adding this .ini file won't disable your ability to earn achievements, and based on my testing it doesn't seem to affect performance. There's really no excuse for a game like Starfield not having an FOV slider, especially given the number of people who suffer from motion sickness without one.