To duplicate a layer in After Effects, you can use the following steps:
1. Select the layer you want to duplicate in your composition.
2. Click the Edit menu at the top to reveal its dropdown menu.
3. Click Duplicate.
You can also use the keyboard shortcut Cmd+D (Mac) or Ctrl+D (Windows) to duplicate a layer.
If you want to duplicate multiple layers in After Effects, you can use either the Edit menu or keyboard shortcut, the only difference being that you need to first select the multiple layers in your composition you want to duplicate. This can be achieved using a standard lasso select, or by manually selecting multiple layers.
I hope this helps!
