If you want to only allow certain types of files for assignment submissions, you can restrict the upload file types when adding assignment details.
In the case of restricting assignments with an odd or unusual file type, try adding it to your course to confirm the file is accepted before requesting students to submit the file type.
Google Drive File Types
If your institution has enabled Google Docs (at the account level) as an assignment submission type, students can connect to Google Docs as a web service to submit an assignment as a Google Doc (.gdoc), Google Sheet (.gsheet), or Google Slide (.gslide). They can also use Google Docs to submit uploaded Word (.doc/.docx), Excel (.xls/.xlsx), PowerPoint (.ppt/.pptx), and PDF files not converted to Google Docs formatting.
When Google file types are submitted as an assignment submission, those files will convert to their Microsoft counterpart file types and appear in the submission as respective Word, Excel, or PowerPoint files. Curve uses the conversion file type for submissions, so if you want to restrict file types to only include Google file types, you must also include the file types for each respective Microsoft file type as well. For instance, if you want to only allow Google Slide submissions, you must include .pptx as a restrictive file type, otherwise Curve will not show the gslide files in the Google Doc tab.
Turnitin File Types
If your institution has enabled Turnitin (at the account level) for assignment submissions, Turnitin accepts various file types and images.
In Course Navigation, click the Assignments link.
Click the Edit button.
Select Online Submission Type
Click the Submission Type drop-down menu  and select the Online option. Click the File Uploads checkbox .
Restrict File Types
Click the Restrict Upload File Types checkbox  and manually enter a list of accepted extensions in the Allowed File Extensions  field.
All file types need to be separated by a comma. You can include spaces, capital letters, and periods in assignment file names.
Click the Save button.