Yes !
You can use the attribute manager (in Options -> Element attributes -> Attribute manager...) to do it.
Open the project from which you want the layer combinations to be copied from, and open the attribute manager.
Once you've opened it, go to the Layer Combinations button, you'll see two windows: in the left one with the combinations of your project, in the right an empty one. Select the combos you want to copy on the left window and click on the button By name... then you'll click on the button Save as... you'll generate an attribute manager file (ext .aat).
In the project you want to import your combinations, do the same, click on the right window then on the Open... button. Select the combos you want and click on the button Append...
That's done ! take a look into the other sections of the window, you'll find you can manage a lot of attributes between your projects !
Felipe Ribeiro Cunha
AC 26, macOS Monterey