Yes, an opportunity amount can be split against different quotas (i.e. for cross-sell opportunities, 30% of the opportunity is contributed to the AMs quota and 70% is contributed to the AEs quota).
You can set up opportunity splits in your Salesforce instance. You can learn more about how to set up opportunity splits in the documentation written by Salesforce.
Contact your Clari CSM before you enable opportunity splits in Salesforce to discuss how you want to configure your Forecast and Opportunities Modules for splits.