A. Overlay the existing FinanceExt model and populate the solution definition.
B. Modify the DefaultModelForNewProject setting in the DefaultConfig.xml file and name the model FinanceExt.
C. Create a new model that extends the existing FinanceExt model.
D. Extend the existing FinanceExt model and populate the project model definition.
Explanation:
https://www.google.com/amp/s/robscode.onl/d365-set-default-model-for-new-projects/amp/