There is quite a lot that would go into creating these visuals, so I’ll address many of the main details here (but still glossing over full implementation of them).
This appears to be reproducible through a combination of elements:
Modified lighting (Shader) to Ceil/Round/Floor (or whichever) the light intensity.
// There's a whole lot more to this, but this is the
// gist of applying intentional color-banding.
float avgLight; // example using a single value for light intensity
// Example: 5 light intensities, ranging from 0-1
// Only an initial light value of 1.0 will be "lost", transforming
// into the same intensity as the (0.8-0.9999) range
float lightBands = saturate(floor(avgLight * 5.0) / 4.0);
A reduced render resolution for the scene. This can be done in numerous ways, but doing so without changing the base display resolution (i.e. the video’s example of 1920x1080 Screen Resolution) would involve setting the main camera’s Rect (Camera.rect) to the target size during OnPreRender(), then changing it back to the base resolution at the start of OnRenderImage(RenderTexture, RenderTexture). Specifically, this approach would keep the UI rendering at the screen’s native resolution while reducing the 3D render resolution:
baseRect = myCam.rect;
scaledRect.Set(baseRect.x, baseRect.y, targetWidth, targetHeight);
myCam.rect = scaledRect;
void OnRenderImage(RenderTexture source, RenderTexture destination)
myCam.rect = baseRect;
// rest of general function usage: Blit(), etc.
Well, I guess those are really the only two primary elements with respect to this question. The video describes an orthographic camera rather than perspective and the water looks like it probably shows reflections, but the light bands and scaled render resolution are a bit more involved to fully implement (especially if you intend to apply lighting changes to both forward and deferred rendering and/or URP/HDRP).
For reference, a post-processing Shader could be used as a substitute for either/both elements, but would potentially have less versatility for lighting-based effects and would potentially be a more-expensive way to render a lower-resolution version of your scene. It’s a valid option, but this is a situation where investing more effort into script and shader-related (lighting) elements could potentially have cleaner/more efficient results overall.