Hi @SABA365,
Thank you for posting in this community.
If you open SharePoint documents in Office Web Apps, then the documents URL will be rendered with 'wopiframe.aspx'. But the document URL in SharePoint search page is the real path of the document. Clicking on the link here does not assume that you are trying to open the file using the Office web app, so the file will be downloaded directly.
Please try the following settings to see if you can get the file to open in your browser:
1.Go to Library settings->Advanced settings->Opening Documents in the Browser. Select "Open in the browser".
2.Please try to add "?web=1" after the documents' URL.
For example: https://myfqfn/sites/projectA/Report.xlsx?web=1
3.Maybe something is wrong with Office Online Server. You can disconnect SharePoint Server from Office Online Server and then reconfigure SharePoint Server to use Office Online Server.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.