Sdkmanager not installed in jetson xavier nx

From: How to Install JetPack :: NVIDIA JetPack Documentation

Assuming your Jetson developer kit has been flashed with and is running L4T 32.3.1 or higher, the following commands will install all other JetPack components that correspond to your version of L4T:

sudo apt update

sudo apt install nvidia-jetpack

To view individual Debian packages which are part of nvidia-jetpack metapackage, enter the command:

sudo apt show nvidia-jetpack