
Samsung Galaxy On7(2016)
The latest firmware for Samsung Galaxy On7(2016) (SM-G610S) is G610SKSU2CTI1 with Android 8.1.0 (Oreo), released on October 28, 2020 for 1 region (CSC). Every official firmware build for SM-G610S, 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/G610SKSU2CTI1
SM-G610S started on Android 6 and has received 2 major Android upgrades; it now runs Android 8.1.0 (Oreo). The newest build, G610SKSU2CTI1, was released on October 28, 2020. No new build has appeared for 72 months, so regular updates for this model have most likely ended.
Specifications of SM-G610, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.

SM-G610L

SM-G611S

SM-G615FU

SM-G6200

SM-G715A
The newest firmware for SM-G610S runs Android 8.1.0 (Oreo): build G610SKSU2CTI1, released on October 28, 2020.
The latest build for SM-G610S, G610SKSU2CTI1, was released on October 28, 2020 (5 years ago).
SM-G610S has had no new firmware for 72 months, so regular updates have most likely ended.
Yes, all firmware files for SM-G610S are 100% official, original, and obtained directly from Samsung servers.
To flash SM-G610S, 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-G610S.