Technically you can, but it’s not a great idea from a hygiene point of view. Bathroom drains, especially toilets, can harbour bacteria and waste that you don’t want anywhere near your kitchen sink. Using the same plunger for both means you risk carrying germs from one area to another, even if you rinse it.
A better approach is to keep separate plungers: one clearly marked for the toilet and bathroom drains, another for kitchen sinks. They’re not expensive, and you can even choose different colours so they never get mixed up.
If you’ve already used one plunger everywhere, give it a thorough clean with hot water and a disinfectant, and then decide its permanent “zone”. For the sake of your own comfort, it’s nicer to know that the tool you use to clear food clogs in the kitchen hasn’t just come from dealing with toilet emergencies.