It will be easier to ID once it has flowers. Looks like it could be Hydrangea arborescens 'Annabelle'.

I agree with the arborscens id. They can get large, although you can keep the height down somewhat with pruning; they also sucker (at least mine does), but near the mother plant.

Look up the proper pruning for arborscens before you pick up the clippers, as they are unlike the "usual" Hydrangea, which is macrophylla.

I cut mine to the ground every year, which I have never done with H. macrophylla.

Do you find that the stems/branches are weaker than non-pruned? That was the argument I saw for not pruning hard.

Hmmm...not sure. They all seem fine. The heads get really big on 'Annabelle' and if they get watered overhead they all lie down on the ground when in flower until they dry off. But otherwise are fully able to stay upright.