Can files be uploaded and submitted with a form?

Yes, that is possible here in JotForm. You need to create a File Upload field inside the form so the user can upload files of any types and limit the file size the way you want. Please check this guide: How-to-Create-File-Upload-Forms

After adding a File Upload field, select it and click the Cogwheel Icon (Properties). Go to the Option tab, change the Limit File Size and File Types to your own preferences.

Related guides:

Changing-the-File-Upload-Size-Limit
How-to-Change-the-Allowed-File-Types-Extensions-in-the-Upload-Field