Interestingly, on the full-sized version of these photos the Stylo 3 made a 4.1MB file, whereas the Stylo 5 produced a 3.5MB file. More details and a smaller file to boot. So we know this isn't just a matter of how much data the camera is saving to disk (ahem, SD).
Often budget cameras show their worst side in low-light. So here's a dark room with some glare from a window. Again, cropped to the center of the image (hiding the aforementioned window) to show detail.
|LG Stylo 3|
|LG Stylo 5|
Even from the tiny preview it's clear there's a lot more detail in the 5. Click for larger views and you'll see just how large an improvement it is. Which is not to say the Stylo 5 is great, just much improved. My ancient Samsung Galaxy S7 still does much better (see some of my other posts for examples of this same shot on that camera).
OK, so the difference in poor light is very noticeable. What about a better lit shot? Here are two photos showing a well-lit outdoor scene with strong shadows. No cropping here; these are the original jpgs.
To conclude: the Stylo 5 is an upgrade over the 3, particularly in low light. Thus, indoor shots almost always look better. Well lit outdoor shots are not really that different between the two, though one might prefer the 3 or 5 depending on your taste. The 3 does tend toward washed out, less saturated colors in most shots. The 5 has better color and is always when there's no harsh shadows. In dramatically lit scenes the small loss in shadow details is detectable, however, even with HDR on.
BUT: the Stylo 5 is still nowhere near flagship camera quality (even flagship from 4 years ago). It might be good enough, though.