The original Rosetta allowed running some Mac OS X / PowerPC applications on Intel-based Macs. It was part of the Intel versions of Mac OS X 10.4 (Tiger), 10.5 (Lion), and 10.6 (Snow Leopard).
Rosetta 2 allows running some macOS / Intel applications on Apple-Silicon-based Macs. It is a part of the Apple Silicon versions of macOS Big Sur (11), Monterey (12), Ventura (13), and Sonoma (14).
If you are actually running the original Rosetta, there is no way to "update it to Rosetta 2". They run on completely different machines and operating systems. If you are using an Apple Silicon machine, and you have already let the machine install Rosetta 2, there is no "update" needed. Rosetta 2 is already installed.