Did this yesterday.
You can freeze in chunks, uncooked. Core and peel, then cut into whatever size chunks you want.
Put straight into a bowl of lemon water (juice of half a lemon mixed with cold water) to prevent browning. Lift out, pack into freezer bags, squeeze out air and seal.
The freezing will break down the texture of the apple, how much depends on the variety, ripeness etc.
HTH.