I created a metallic material by increasing its metallic property and slightly decreasing its roughness property. The material shows up nicely in the preview. I cannot tell if the render is normal. Should I add more objects to see if they reflect? The cube doesn't look shiny at all. Here is what my render looks like:
Your screenshot looks like you're using Eevee. Contrary to Cycles, this is no raytracing engine so many things like reflections, refractions etc. do not work naturally. I'll just say it simply like that, I'm not going to explain technical details here (since I'm not competent enough).
I tried to recreate your scene and your material and this is how it looks like in Eevee to the left (more or less like your screenshot) and Cycles to the right:
In Cycles the reflections are calculated automatically (unless you disable visibility in reflections but we're going to dive into that), in Eevee by default they are disabled. You can turn them on by checking Screen Space Reflections in the Render Properties.
After enabling them the result looks immediately better without even optimizing the settings for the reflections as you can see in this comparison:
Of course reflections look better and more exciting if there is more environment to reflect. So more objects in the scene or an HDRI as background might help to make it look better. Of course there is always room for improvement on the material itself as well, since in real life no surface is perfectly plain smooth and clean, but I'm not going to write a tutorial on advanced shaders here ;)
Just one last tip: when trying to recreate your material I found that presumably you have set the Metallic to something between 0 and 1. You can do that for artistic reasons, but if you're trying to make realistic materials, something is either a metal or it is not - so usually you would use 1 or 0, nothing inbetween.
You can use a light source to test the metallic levels. However if your render has no texture, it'll come out white when exporting. Seems like you've used the node to create the metallic effect but you need to add some sort of texture even if it's just a color. For example, if you use black for the texture, then add the metallic effect, your result will be a metallic black object. Without texture it's just white with no effects.
*Still new myself, somebody else may have better input.
