'Create From Template' in MUX was introduced in v15.9.2.
Blueprinting dictates what will show up in the Create page of a project when trying to create a project from template. However, the custom required fields will show up which are not in the Blueprint.
15.9.2 and above
The Create from Template requires all required fields to be populated when a project is created. Hence, even if a required field is not in the Blueprint, the system will force the user to enter value for the project.
If there is a business requirement that not all required fields needs to be populated at the time of creation, then the required fields will have to be populated with a default value at the attribute properties level.
The below link from the product guide gives more information about Create from Template:
The Modern UX does not follow the Classic UI required fields.