Ask HN: To Mobile App Devs: How do you change your app's UI?

Hello mobile app devs, I have been trying to find out solutions for dynamically changing certain UI elements in my app without releasing a new app version.

For e.g. I want to test whether an onboarding string A is better than onboarding string B. Or show a different menu items to certain users.

How do you guys control the display logic without releasing a new app version?