Hi @BibiFrazine ...
When I was a Canvas admin in higher education, during my last 1-2 years there, I had been playing around with using a *.csv file (created in Microsoft Excel) to make a file that I could import into Canvas to "bulk upload" Outcomes at the Canvas account level. Unfortunately, I don't have an exact sample of that file any longer, but I do know that there is documentation available that you could reference:
Outcomes Import Format Documentation - Canvas LMS REST API Documentation (instructure.com)
I remember that I was able to nest outcomes within outcomes, but again, I don't remembrer exactly what my file looked like. I hope that this link may be of some help to you, though.