Rule of Third technique is being use by many photographers since it is more pleasing to the eyes at first glance. Rule of third is not that complex like its name. To apply this rule to your photo whether you shoot it with phone, DSLR or mirrorless, just enable grid mode and align your foreground object to the left or right within the intersection points.
One question frequently ask is "why we use Rule of Third". Using this technique mean that the object is not in the center So it make the whole picture wider and the foreground object does pop out more from background. It draw attention from to viewer's eyes to focus more on composition rather than the center of the image.
here are some samples being applied with this technique
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Last question is does it apply on every shoot. The answer is no so why, Rule of third do work better with portrait type of shoot when you want one object to stand out. It will also work on few landscape mode but you should apply other photography rule to improve overall images.
For those who never follow this rule then do it for once and you will see a different field of view in picture.
Disclaimer : I am not an expert in photography field but i did learn a lot in this field since 2015.