
Samsung Galaxy S6 (DoCoMo)
The latest firmware for Samsung Galaxy S6 (DoCoMo) (SC-05G) is SC05GOMU1CRI2 with Android 7.0 (Nougat), released on September 19, 2018 for 1 region (CSC). Every official firmware build for SC-05G, 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/SC05GOMU1CRI2
SC-05G started on Android 5 and has received 2 major Android upgrades; it now runs Android 7.0 (Nougat). The newest build, SC05GOMU1CRI2, was released on September 19, 2018. No new build has appeared for 98 months, so regular updates for this model have most likely ended.

SC-02D

SC-02B

SC-01E

SC-01D

SC-01C

SC-03D

SC-04F

SC-04E
The newest firmware for SC-05G runs Android 7.0 (Nougat): build SC05GOMU1CRI2, released on September 19, 2018.
The latest build for SC-05G, SC05GOMU1CRI2, was released on September 19, 2018 (8 years ago).
SC-05G has had no new firmware for 98 months, so regular updates have most likely ended.
Yes, all firmware files for SC-05G are 100% official, original, and obtained directly from Samsung servers.
To flash SC-05G, 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 SC-05G.