Do you want to find a local maximum? If so see the islocalmax function.
Do you want to find a place where your data changes significantly? If so see the ischange function.
Do you want to find, clean, or remove the outliers? If so see the isoutlier, filloutliers, and/or rmoutliers functions.
All the functions I mentioned are in the Preprocessing Data section of the documentation. If none of them do exactly what you want, perhaps you can combine them with other data preprocessing functions to achieve your goal.