When you create a link to a file in SharePoint using the standard method, it opens in the browser by default. To make the file downloadable instead, you can customize the link to trigger a download rather than opening the file. This can be done by adjusting the file’s URL or using specific download settings in SharePoint.
Navigate to your library and select the file. Click on three dots (…) and select Download
In your browser click on the download icon open the Download History
Copy the link from your download history:
It looks similar to: https://TENANT.sharepoint.com/sites/EWZ/_layouts/15/download.aspx?UniqueId=cf6f2e20%2D8050%2D439e%2Dbf00%2D8827ca8bac19
You can also create the downloadable link on your own by replacing TENANT, SITENAME and UNIQUEID with your values in the following template:
https://TENANT.sharepoint.com/sites/SITENAME/_layouts/15/download.aspx?UniqueId=UNIQUEID