The Short Version
In an article from the National Sleep Foundation regarding how much sleep kids need, they state that for a 2 year old it is recommended that they get between 11 and 14 hours of sleep per day but also acknowledge that anywhere between 9 and 16 hours may be appropriate depending on the individual. Anything outside of that range was categorized as "not recommended". So it seems like your toddler is within an acceptable range.
Looking ahead to 3 year olds, the amount of recommended sleep drops a bit, so I'm not worried that your child might be getting to the point of needing less sleep a little quicker than average.
The Longer Version
In a study published in the Sleep Health journal (which is affiliated with the National Sleep Foundation (an American thing)), the researchers gathered a large group of sleep related studies, papers and articles and distributed them to members of various sleep experts and medical organizations, which included the American Academy of Pediatrics. These members were asked to review the material, and then vote on whether a given amount of sleep was appropriate for someone in a given age group. The researchers compiled all the votes and grouped the hours of sleep into categories based on how many people in the voting group agreed or disagreed on the appropriateness of the amount of sleep for someone in the given age group. The results are as follows:
From the same research paper cited above
The study also has a caveat that all this is talking about how much time is actually spent sleeping compared to time in bed. The research material used often did not make the distinction, which they state would bias the numbers towards the higher end of what is really needed. They also state that no mention was made about the quality of sleep and how that affects the recommendations. These (along with a few other things they mention in the paper) are just some things to keep in mind when evaluating how your child compares to these recommendations.
Given that data, 10 hours for 2.5 year old (right between the 2 and 3 year olds) doesn't seem out of line at all to me. As long as she seems to be sleeping well and is happy and healthy, she should be just fine.