Skinny apple tree
Thank you for the image.
It is normal for a number of very small apples to drop. If they didn't, the crop would be so heavy that branches would break.
That, said, it's important to remove most of the tiny apples by the time they become the size of an olive. The reasons are several: 1) to avoid broken branches and 2) to develop large apples with high quality.
To remove the excess, keep only the largest central apple in each cluster. The exception would be if the largest one is damaged. In that case, keep the next largest apple in the cluster.
See ""Thinning Fruit" - https://extension.oregonstate.edu/gardening/berries-fruit/fruit-thinning