To install Next Gen OS v3.7, you must have a custom recovery like installed on your device.
The v3.7 update focuses on delivering a "next-generation" experience on hardware limited by 1GB of RAM and an Exynos 3475 chipset. next gen os v3.7 for j200g
While Next Gen OS offers a visual upgrade, users should be aware of potential stability trade-offs common in J2 custom ROMs : To install Next Gen OS v3
Integrated tools like Device Maintenance (Smart Manager), Game Launcher, and native call recording are often ported into these builds. Installation Guide for SM-J200G To install Next Gen OS v3.7
Next Gen OS v3.7 for Samsung Galaxy J2 (J200G): Performance Boost and One UI Experience