No official "Next Gen OS v37" exists from Samsung. The last official firmware for J200G is Android 5.1.1 (Lollipop).
What you're referring to is likely a custom ROM (unofficial) from community developers (e.g., on XDA or Telegram), possibly based on LineageOS / AOSP.
“You’re insane,” said Leo, her cousin and shop owner, wiping grease off a soldering iron. “That phone has 512MB of RAM. Your OS has microservices.” next gen os v37 for j200g
Features updated wallpapers, a modernized gallery app, and a new lock screen style. 4. Installation Requirements Quick Answer No official "Next Gen OS v37"
A computer, a reliable data cable, and a microSD card for storing ROM files. Software Tools: Odin Tool: Used on the PC to flash recovery images to Samsung devices. TWRP Recovery: on XDA or Telegram)