The images you use as sources and output have a big impact on the realism of your renders. This video from dimensiont on YouTube looks at the value of using HDRI images when doing renderings. I think the video could use a different soundtrack, but the examples given are convincing.
In the video, you’ll see the difference in colors, shadows, lighting and reflections between high dynamic range images and formats like jpeg and png. The video does a great job of making the difference in contrast and detail obvious. It also gives you some hints to the value for different lighting environments though I’d say the video could use more lighting examples.
Watch this video if you’re working on placing made objects and people into real-world environments or struggling to fine-tune a render.