
Samsung Galaxy S6 Edge
The latest firmware for Samsung Galaxy S6 Edge (SM-G925R4) is G925R4TYU4DRI1 with Android 7.0 (Lollipop), released on September 9, 2018 for 1 region (CSC). Every official firmware build for SM-G925R4, newest first: one row per build with all regions (CSC) that received it.
SM-G925R4 started on Android 5 and has received 2 major Android upgrades; it now runs Android 7.0 (Lollipop). The newest build, G925R4TYU4DRI1, was released on September 9, 2018. No new build has appeared for 98 months, so regular updates for this model have most likely ended.
Specifications of SM-G925F, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.

SM-G935TZK

SM-G930AZK

SM-G935AZS

SM-G935TZS

SM-G935AZK

SM-G935TZD

SM-G975WC

SM-G975FC
The newest firmware for SM-G925R4 runs Android 7.0 (Lollipop): build G925R4TYU4DRI1, released on September 9, 2018.
The latest build for SM-G925R4, G925R4TYU4DRI1, was released on September 9, 2018 (8 years ago).
SM-G925R4 has had no new firmware for 98 months, so regular updates have most likely ended.
Yes, all firmware files for SM-G925R4 are 100% official, original, and obtained directly from Samsung servers.
To flash SM-G925R4, 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-G925R4.