Hi,
For other types of file attachment to email. You have to work the other way round.
That is, first go to the file you which to email. Select it and SHARE.
There will be options for sharing where your Outlook mail will be one of them.
under W10M preview you do have the option to add an attachment within the email you created. So not too long and you'll get it too (just tested here with Word doc from OneDrive).