If you have org admin privilege for your organization, you can clone a course. Clone will create a replica of an existing course and enroll teachers.
First go to home page. Make sure to select the "org admin" on the top-left and "List View"
Select the course you want to clone and select "Clone" button -
Select the options.
Special attention needs to be paid to the following options -
Method
Most of the time you would want to select "Clone by copy" where child will have its own copy of the content.
Select "Clone by reference" if you want the clone to not have its own copy of the file system which includes starter code, scripts, etc. In that case if the parent changes the content it will automatically be reflected in the children.
Teacher Editable
Select the flag if you want teacher to be able to change the content. In most case, you would want to select it.
Inherit Published State
If selected assignments will have the same Published flag as the parent. Otherwise assignments in children would be in unpublished state.
For documentation to update clones visit this article