You're referring to the 4g Magisk module!
First and foremost, it is critical to clarify a fundamental misconception: no software module, Magisk or otherwise, can create 4G signal where none exists. The physical capabilities of your phone’s antenna and the strength of your cellular carrier’s signal in your area are hardware and infrastructure limitations. A Magisk module cannot turn a 3G-only tower into a 4G LTE tower, nor can it add a missing LTE antenna to your phone. So, what do these modules actually claim to do? They do not boost raw signal power but rather attempt to optimize how your device connects to, maintains, and prioritizes the existing 4G LTE network. 4g magisk module
Before installing any 4G module, check the XDA Developers forum or the module's GitHub page for your specific device model. You're referring to the 4g Magisk module
To understand the value, you need to understand two key Android components: Magisk Root: The device must be rooted using Magisk
4G Icon Replacer: Replaces the default LTE status bar icon with a 4G icon.