What would happen if I topped this tree-plant?

My son dropped this homeless plant on me today. I love it, I can always find a place for it outside, but I asked, “What am I gonna do when I have to bring him in for the winter??”
Chris says, “You have 10 foot ceilings, so he has another foot to go!”

I think I need a beeger house.

This is what it all looks like, standing in the living room, looking out on the front porch.

He is just so TALL. It’s a pine, and it smells like Christmas. I’ve had plants, large plants, for years and years, but I’ve never had a plant like this before and I’m clueless.

If I topped him, what would happen?

Any other advice is welcome, too.

(Yes, he’s been repotted in a larger pot, had a shower, and a nice drink of water.)