Leonardo da Vinci was an Italian painter in the renaissance period. During this time, the golden section (rule of thirds) was invented. In short, this meant that paintings were often split into three (not literally) and the focal point was often in the middle. This was revolutionary for this period and distinguished the renaissance’s style.
Leonardo da Vinci used murky warm green and yellow hues in the Mona Lisa, creating an old, and refined feel to the painting. He uses the rule of thirds in this piece, making Mona Lisa the focal point.
His other oil paintings are much like this too, making the portrait understandably the focal point. Often, to bring out the pale tones he uses to depict models, his backgrounds were dark and detailed, giving the audience and viewers a lot to discover about the piece, showing he could use depth within a painting.
i dont know if thats ok, hope i helped :)