It actually depends on where it’s located the aspects it makes where Leo is in the chart (if you are Leo rising this would be your most important placement for example). It may depend on if this is a day or night chart I am not sure some places say sun during the day is more powerful and moon more at night.
My experience is the sun is not the full personality of the individual like most online info says that is the ruling planet (main ruler of the sign on the cusp of the first house) this is especially true if the sun is in a very different sign from the chart ruler. I think if you have 3 or more things in one sign other than the chart ruler that sign still becomes most important though.
This could be a major thing or it could be just an aspect of you that’s not very pronounced you would have to focus on the whole chart. This is exactly why a lot of people don’t believe in astrology cause their sign doesn’t fit them. They didn’t look at the full chart.