You do not say the type of your apple tree root stock or variety is but here are some options:
The central/main leader structure is based on a fruit tree's natural upright growth form. Central leader pruning benefits apples, pears, and more. There are different pruning and training structures for different types of fruit trees. The central leader, or main leader, structure is recommended for fruit trees whose branches naturally have more of an upright growth habit, rather than a spreading nature. This structure calls for a single trunk with scaffold limbs (think like a Christmas tree form), which allows for adequate light exposure throughout the tree's canopy. Light is essential for the development of quality fruit. Once again, the central leader structure is based on the natural growth habit of the trees. These fruit trees tend to have more of an upright growth habit, and the central/main leader structure keeps the canopy open to light and air circulation so that fruit production and overall tree health are maintained.
Know the type of tree you will prune so that you know how to approach pruning it.
You can prune an apple tree any time of the year without hurting it, but late winter, just before spring, is probably best and you'll still be able to influence the tree's spring growth.

There are several main objectives to pruning an apple tree:
Controlling the height of the tree, so that most of the fruit doesn't grow out of reach;
Developing good limb structure for strength, fruit production, and the general health of the tree; Encouraging a plentiful supply of new limbs, which will begin to bear fruit their second year; and ridding the tree of damaged or diseased growth.
The overall size of the tree depends primarily on its rootstock and innate vigor. Most apple trees are grafted onto dwarf or semi-dwarf rootstock. (Take care when you plant a new apple tree not to bury the graft, where the fruiting stock joins the rootstock. This will ensure that the fruiting stock will not begin to produce its own roots and the tree will keep its dwarf or semi-dwarf height.) Even so, you'll want to monitor the height of your tree to be sure it doesn't outgrow the spot you've picked for it. Once it's as high as you want it to be, prune the central "leader," the main upright limb, back to a lateral branch. Then keep monitoring the height year by year.
Inspect your tree for limbs that branch from the central leader either too sharply upward, forming an acute angle, or at too wide an angle. Acute angles tend to trap bark as they grow and can lead to splitting later. Branches that grow at too great an angle from the vertical tend to be weaker. They also encourage "water sprouts," the unproductive upright shoots that need to be pruned off mid-summer every year. The ideal angle between the central leader and lateral branches is about 60 degrees.
In general, encourage branches to grow toward the outside of the tree and eliminate those that grow toward the center or cross other branches. You want air and light to penetrate the foliage to the center of the tree as much as possible.
Different kinds of apple trees have different ways of setting fruit buds. Most modern apples are spur-bearing. Many older varieties are tip-bearing. This is obviously very important for how we prune the tree so as not to cut off the fruiting wood. If you're in doubt, as long as you know the name of your tree you can ask at your local nursery or look it up in a good garden book or on the Internet.
Once your tree has matured and begins to produce fruit, expect new branches to bear their best for several years (perhaps three to five years) and then taper off. You'll want to prune off older branches that have begun to produce less in order to encourage new ones. This practice will help you have a more-or-less steady crop over a period of years.

https://extension.oregonstate.edu/catalog/pnw-400-training-pruning-your-home-orchard