That’s your opinion, not a fact.
And the issue with that is you’re only seeing it as two sides and a fence-sitter.
Centrists form their own views and positions, independent of the parties on either side.

There’s no forcing them to take a position, they already have one.
And when they have to vote for/against legislation changes, they’ll side with whichever option aligns most closely with their views.

US pseudo-centrism is right wing though, which might be what you’re confusing real centrism with.