This will depend on how you choose to set up the assignment.
1) If you want or need student papers to be Google Docs, perhaps as part of the creation of their online portfolio, you should consider using Google LTI 1.3. Students will automatically receive a copy of whatever template you give them (including a blank Google Doc) which they can submit through the assignment page.
2) For a more traditional method, you can have students upload their paper. You can even specify what file types you want Canvas to accept (e.g., .docx, PDF, etc.)
3) You can also set up assignments for peer review
Using Google Assignments to create/submit student papers (Google)
How do I use peer review assignments in a course? (Canvas Community)
How do I create an online assignment? (Canvas Community)f
While Canvas does not have SafeAssign, the university has procured Turnitin.
Using Turnitin with Canvas (Turnitin)