https://wccftech.com/galaxy-s9-note-9-and-others-to-get-bixby-button-remapping-in-a-future-update/

Samsung managed to get a lot of things right post the Galaxy S8. The super AMOLED panel and curved display were a sight to behold. The dedicated Bixby button, however, was (and still is) a feature that nobody asked for but are stuck with. To make matters worse, Samsung didn’t let users change what the button does and doing so involved using third-party apps or root. At best, one could disable the button which left you with a button that does nothing. Yesterday, we found out that Samsung would let users remap the Bixby button on the Galaxy S10. Today, Samsung confirmed in a blog post that the feature would make its way to older devices.

To offer users more freedom to utilize Bixby’s handy button, the Galaxy S10 introduces Bixby Key Customization.5 Now, you can customize the button to launch Bixby with either a single or double press, and map the other option to launch your favorite app or Quick command. It’s just another convenient way to make Bixby your own.