Not all images require manipulation, most times it depends on what you’re trying to achieve as a photographer. Photo manipulation involves the alteration of images using different methods and techniques to achieve a particular or desired result. It’s a great deal to be skillful in manipulating images but this requires a lot of artistic approaches.
Photo manipulation didn’t begin as a result of the invention of editing software. However, photographers, editors, and retouchers have been using different techniques to create new work out of existing assets for over a century. Photo manipulation can be used for artistic pursuits such as surrealism.
The below link will help improve your photo manipulation skills.
https://www.adobe.com/creativecloud/photography/discover/photo-manipulation.html