Windows+R. Enter %appdata% in the run and follow the path below to reach the desired folder, which is:
...AppData\Local\BusSimulator21\Saved\Config\WindowsNoEditor

Find the Enigne.ini file.
Associate it with Notepad++ or Notepad.
The following should be modified:
(Scroll to the bottom and insert)
[SystemSettings]
r.Shaders.Optimize=1
r.UseShaderPredraw=1
r.Streaming.HiddenPrimitiveScale=0.5
r.Upscale.Softness=0
r.RefractionQuality=0
r.Shadow.MaxResolution=512
r.Shadow.MaxCSMResolution=512
r.Shadow.CSM.MaxCascades=15
r.Shadow.CSM.TransitionScale=0
r.Shadow.DistanceScale=0.2
r.Shadow.WholeSceneShadowCacheMb=720
r.ScreenPercentage=95
r.DepthOfFieldQuality=0
r.DepthOfFieldQuality=0
r.HalfResReflections=1
r.LightFunctionQuality=0
r.MotionBlur.Max=0
r.MotionBlurQuality=0
r.MotionBlurQuality=0
r.DefaultFeature.MotionBlur=0
r.SceneColorFringe.Max=0
r.SceneColorFringeQuality=0
r.SceneColorFringeQuality=0
r.Tonemapper.GrainQuantization=0
r.Tonemapper.GrainQuantization=0
r.Tonemapper.Quality=0
t.OverrideFPS=144
r.SSR.Quality=0
r.EarlyZPass=0
r.Streaming.Boost=0.9
r.ReflectionEnvironment=0
sg.ViewDistanceQuality=3
sg.FoliageQuality=3
Compat.UseDXT5NormalMaps!=True
r.Streaming.MipBias=3
r.MaxAnisotropy=2
r.Streaming.PoolSize=512
r.BlurGBuffer=0
r.AmbientOcclusionLevels=0
r.AmbientOcclusionRadiusScale=1
r.RenderTargetPoolMin=600
r.LensFlareQuality=0
r.EyeAdaptationQuality=0
r.BloomQuality=0
r.FastBlurThreshold=0
r.Upscale.Quality=0
r.SceneColorFormat=1
r.DetailMode=2

The modified files can be found here. A Normal or SuperLow* version.
https://mega.nz/folder/eB0EFTZR#82RCk27wqXafb7XiQp4xZA
*From a laptop or weak computer. 720p resolution low preset, except for the viewing distance, which can handle a medium setting.

Have Fun ! :D