
Samsung Galaxy S6 Edge+
The latest firmware for Samsung Galaxy S6 Edge+ (SM-G928R4) is G928R4TYS3CRJ1 with Android 7.0 (Nougat), released on September 30, 2018 for 1 region (CSC). Every official firmware build for SM-G928R4, newest first: one row per build with all regions (CSC) that received it.
Each firmware build has its own page at https://samfirm.shop/build/{PDA}, where {PDA} is the build number from the list above. Example: https://samfirm.shop/build/G928R4TYS3CRJ1
SM-G928R4 started on Android 5 and has received 2 major Android upgrades; it now runs Android 7.0 (Nougat). The newest build, G928R4TYS3CRJ1, was released on September 30, 2018. No new build has appeared for 98 months, so regular updates for this model have most likely ended.
Specifications of SM-G928, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.

SM-G928A

SM-G925A

SM-G920X

SM-G9298

SM-G935TZK
The newest firmware for SM-G928R4 runs Android 7.0 (Nougat): build G928R4TYS3CRJ1, released on September 30, 2018.
The latest build for SM-G928R4, G928R4TYS3CRJ1, was released on September 30, 2018 (8 years ago).
SM-G928R4 has had no new firmware for 98 months, so regular updates have most likely ended.
Yes, all firmware files for SM-G928R4 are 100% official, original, and obtained directly from Samsung servers.
To flash SM-G928R4, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SM-G928R4.