• Update to the latest Stable Version and Proton Experimental / Proton Hotfix as Valve has put fixes for RE4 remake in those
  
• Use Cryoutilities 2 with all recommended tweaks and at least a 12gb swapfile
• Set your deck's Vram to 4gb (shown in video above)
  
• It is recommended that you install the game to an SSD if you have it on your deck.

Put this in the launch command options
this will lock the framerate with better input latency, locking RE4 at 30 with any other method will cause playability issues.

In Game
1280*800
60Hz
Variable Framerate (remember Mangohud limits it, leave this alone in-game)
Fullscreen
Vsync OFF
Cinematics Full HD
FidelityFX SR2 (FSR 2) Quality
FSR 1 NONE
Image 100%
Rendering Mode: Normal
AA Off
Textures: High 2GB
Filtering: Aniso x4
Mesh Quality: High
Shadow Quality: Medium
Shadow Cache: On
Contact Shadows: On
AO: SSAO
Volumetric Lighting: Low (you can raise to medium after the opening)
Particle Lighting: High
Bloom: On
SSR: On
SS Scattering: On
Hair Strands: Off
Dismemberment: On
Persistent Corpses: Many should be safe. Low if you are CPU bound
Corpse Physics: Low
Diverse Animations: On
Motion Blur: Off
Rain: High
Terrain Tesselation: Off
Destrutctible Enviroments: On
Lens Flare: On
Lens Distortion: OFF
DOF: On
RI Lights: High
RI Effects: Low

On Display Settings:
Set FOV as high as it will go.

Steam Overlay:
60Hz
Leave the cap at 60 as it comes by default, since it's not capped from here.
Do not enable Allow Tearing
Cap TDP at 13w. The opening (and certain areas) do not play well with caps. I would turn the cap On only after the first village fight

Post Notes:
If you need extra performance turn Screen Space Reflections off as it's the best tradeoff of gain vs visual loss.
Try experimenting with raising shadows to high as in most areas the difference should not be that big.

Set to 40hz
Set to 40 Fps
DO NOT ALLOW TEARING

You can also try mangohud cap by using this command instead of capping from the steam overlay
YMMV. On 30 you MUST use mangohud. You can choose a limiter for 40.

In Game
Select Preset and Choose the LOWEST PRESET.
Now we change these values:

1280*800
60Hz
Variable Framerate
Fullscreen
Vsync OFF
Cinematics Full HD
FidelityFX SR2 (FSR 2) Balanced
AA: TAA
Rendering: Normal
Textures High 2GB
Filtering: Anisotropic x2
Shadow Cache: On
Contact Shadows: On
Lens Distortion: OFF
DOF: On
Destructible Enviroments: ON
Diverse Animations: ON

On Display Settings:
Set FOV as high as it will go.