where is the launchpad on new iMac

If Launchpad isn't on your Dock you can use the Finder "Go" menu to go to the Applications folder and then drag the Launchpad app from there to the Dock.

The iTunes app for Macs was discontinued and replaced. It cannot be installed on Macs that are running Catalina, Big Sur or Monterey. See the following for information about the replacement apps: What happened to iTunes? - Apple Support

iTunes was retired years ago, there is now the Music app and TV app. Launchpad is where it always has been in the Applications folder.

How were you used to accessing it on your old Mac? For example if you used to get to Launchpad from the Dock then go to the Applications folder and drag Launchpad to the Dock. If you used to use a key on your keyboard to access Launchpad then customize a key or keyboard combination to access it.

• If you need help on either creating an item for your Dock please navigate to: Mac Basics: Using the Dock - YouTube
• If you need help creating a keyboard shortcut: Create Your Own Custom Mac Keyboard Shortcuts - YouTube

I would also strongly recommend looking over macOS Monterey - Apple