When i bought my second hand car, the engine bay was stunning beautiful...definitely they washed it and sprayed something to give it a new look. does anyone know what can i use to give my car a new look. thanks in advance.

I use this method when I swap over to my summer tyres;

 

 

And this method for the rest of the time;

 

 

I use finish from autosmart, can be applied onto a freshly washed wet engine and left to soak into the plastics, it can also be diluted down to use as a tyre dressing or diluted even further as an interior dressing

You just need to be quite careful with too much water in close proximity to the engine and electrics, especially if it's a new area of cleaning to you. Those video links above are helpful

For me I take the approach of only applying the water I absolutely need under there, so generally tend to mist over the areas to clean, clean down and then dry with a separate microfibre. Then I use 303 Aerospace Protectant to give some protection, which leaves a nice saturn finish and decent durability;
https://www.polishedbliss.co.uk/303-aerospace-protectant