This year has produced a tremendous set of apples and pears. There are too many per cluster. If you don't want to cry two months from now that all your apples are falling half-grown, then you should thin them. With a small clipper, cut out all the apples per cluster other than the biggest and best. Usually, it is the centre one, but not always. Allow several inches between apples. Also pears need this, but they generally take care of themselves, so I'm really reluctant with my young pear tree, since I haven't got a full-size pear off it yet! Spray after thinning.
The orchards have powerful sprays to thin the apples, but we don't so it is a necessary painful exercise.