There are some small and larger kinds. The small hummock-forming ones, such as Dissectum, are only one metre tall or so, while the larger green or purple kind can reach ten emtres eventually. Obviously it is easier to provide shelter for the smaller kinds.
Is Japanese acer a good choice for my area – how high will they grow?
Japanese acer or maple is a lovely small tree but does not take well to harsh winds, especially if there are salty gales. It needs good shelter. If you are near the coast at Blackrock in Louth, there must be other trees to provide shelter.