In a story, your imagination will have to work according to the character that is being talked about, and the better it is portrayed and describe, the better will it be understood and internalized by the reader.
It is indeed a great and tasking challenge and a bit more complicated in nature than just creating a simple static character. When you are planning on making an effective dynamic character here are a few traits and features that you may need to create to make the story it evolves in more realistic.
The personality of the character to be dynamic is one of the key features that you will want to look into, with that reflecting its main core values that will make of the persona you want to portray and introduce. Another factor that will make your character dynamic and realistic is to give flaws to its personality and do not be afraid to blemish your character and that will also give a twist to the story.
One more specific is the values and passions of the character that will show what they want in life, what their fear is, what challenges them. To make it more realistic, you can include what are the things that your character loves to do, is passionate about, something that makes the most of what they are. Also, to make it more unique, you can add something that can be a distinguishing mark or attribute on your character, like mannerisms, habits, or gestures that make them distinct from the other characters.
A dynamic character evolve in the entire story, like from pitiful to fierce, poor to being rich, bullied to being a fighter, something of the likes that transitions the life experience.
This is a bit complex as you will need to carry out the consistency of the dynamic character you want to convey in your story, and how it will also evolve as the plot and scenes changes that will drive the idea of the entire context of the story.
With the right skills, imagination and the right tools, it will not be hard to create the kind of person that you want the character to have, from all its aspects, personalities, attributes, and everything else that can make it an effective dynamic figure your readers will visualize and understand.
Learn everything that you can, make your dynamic character the kind that will relive in the minds of your readers and will cultivate the interest in them to read on to find out what transpires about the person at the end of the story.