[AstralStorm]

You're as free to get another job as your wallet and opportunity allows you. Usually that is not worth a lot.

It also depends on what you're disagreeing about and whether your manager has enough of a pull to get it changed.

Usually rank and file employees are barred from expressing opinions about strategy at all. Permission or not, you will get ignored. The best you may get is more work as an experiment, with little reward and low chances of success.