My basil plants are thriving too much.
This is my thai basil:
And in the same pot lemon basil:
I've topped them quite a lot, as you can see in the bushy growth pattern.
They already started flowering months ago, even before I put them into the big pot. I read online that you just have to snip them off, and done.
But there are basically only flowers coming, and I don't want them to waste all their power into developing seeds.
Is this normal and just a part of their lives when they reach a certain size?
I'm aware. But even when I lived in places it got below freezing I kept basil perennially. I'd move it into pots in the winter and put it in a sunny window. After drenching it in neem/ citrus oil to kill of the bugs.
Im near certain Ive seen people cultivate basil into little trees. Ive no luck growing it, but you can keep annuals alive through winters doing like you suggest.