From my experience, rooted Samsung devices still recieve updates. But KNOX-protected stuff such as Secure Folder and Samsung Pay stops working. Google's SafetyNet may also get triggered, rendering several apps such as Netflix unusable (unless some steps are done).
I rooted my Note 2 before and whenever I asked for updates, Samsung denied it. A msg stated that i modified the phone and i needed to dwnload the firmware thru Kies. my note 2 phone stuck at kitkat 4.4..now i have a new samsung phone and i read about magisk app to root an android phone...any idea....
I had a Galaxy Grand Prime that was able to proceed through updates whilst rooted, given the software is stock; meaning root should be (temporarily) removed before updating.
Modern devices require your bootloader to be unlocked to be able to root in the first place. You will (probably still) need to remove it temporarily if you update your device, but an update shouldn't re-lock it. You'll just have to root it again the same way you've rooted it before, sans the need to unlock the bootloader.
Please note that the Magisk app *does not* root your phone by itself, the app only does root and module management. You will have to install the core Magisk on your own, either by using a custom recovery (e.g. TWRP) or by patching your device's boot image and/or ramdisk.
