Dunlop0078 :
Well first you will need to downsample your 1080p resolution to 720p or whatever abysmal resolution its runs at on consoles, im not sure if you can do that in game you may need a third party tool or their may be an option in nvidia control panel that will give you the most drastic improvement in frame rate. If you cant figure that out then just run it at 1080p native assuming your monitor is 1080p, it should be able to push it somewhat well on lower settings.
I would agree with aaron probably medium-low settings short distance fade which is how close you have to be to objects and landscapes to see them at full detail. And turn off any hevy anti aliasing like MSAA, texture filtering is probably on 4x or so on consoles, no ambient occusion if their is some it will probaly be SSAO. And you will probably want to turn off god rays.
first: both ps4 & xb1 run fallout for at 1080P NATIVE, and now the ps4 pro runs it at 1440P NATIVE with other graphical enchantments like various higher draw distances and better god rays
second: anti aliasing used is TAA with "maximum quality in textures*, alpha effects and geometry across the game, lowest grass setting, while other fade settings are broadly set to medium quality equivalents, buildings on the horizon run with 'distant object detail' set to high, shadow distance setting = medium preset, medium god ray setting(480x270), screen space ambient occlusion = on, Otherwise, most other settings are identical between PC and console - down to the screen-space reflections, motion blur, and water shaders during rain. All told, we're looking at substantial PC advantage in draw distances, shadows and god rays. But it's ultimately the same core asset-work and geometry shared between all formats. "
*=before the last pc texture patch where you need a nasa pc
you would think that someone on tomshardware would do better research but instead we have the usual "console setitngs? ugg 480p and lower than low", sorry to disappoint you, but Fallout 4 is almost a 1:1 on PC/consoles, especially with ps4 pro now, only real difference is FPS