It looks more like a bush now, but I'm wondering if it will grow into a tree?
It grows like a tree, relatively slow. I don't agree with George's answer. My olives tree are taller than 4m, and not so old. The younger one, I transported in a car around 7 years ago, and now it is taller than 5m.
But the worst part about olives are the roots. They grow fast and will eventually surface, so I think it needs to be planted with more distance to edges.
In any case, olives are quite resilient, but cold can be a problem (from cold, every 10 years or so I see them very damaged, but within a year, they will recover fully), so you can prune heavily and even move them.
Yes, it will grow into a tree. Depending on conditions, this could take a very long time and they can live for well over a thousand years. The ultimate size will depend on the cultivar - wild trees will make between 8 and 15m but may take hundreds of years to get there. Most cultivars will remain substantially smaller. It is unlikely to reach much more than 4m in your lifetime, but will develop a woody trunk.