Change the default link type when users get links for sharing
When a user wants to share a document or folder, they can get a link to it to send to others.
SharePoint Online supports three types of links: Anonymous access links (accessible by anyone), internal links (accessible only by users within your organization) and direct links (accessible only by users who you specify when you create the link). As a SharePoint admin, you may want to enable users to send anonymous access links (as these provide the smoothest experience) but you may not want it to be the default link when the user opens the Get a link dialog box.
You can set the default type of link to something more restrictive, while still allowing users to select other types of links as needed. This setting can be configured both globally for SharePoint Online and at the site collection level. The global setting acts as a default for the site collections. As a SharePoint admin, you can change this setting for any site collection.
This setting applies only to modern sites.
This setting does not affect Outlook Web App, Outlook 2016, or Office clients prior to Office 2016.
To change the setting in the classic SharePoint Online admin center:
Sign in to https://admin.microsoft.com as a global or SharePoint admin. (If you see a message that you don't have permission to access the page, you don't have Office 365 administrator permissions in your organization.)
In the left pane, select Admin centers > SharePoint. If this opens the new SharePoint admin center, select Classic SharePoint admin center in the left pane.
Change the default link type (SharePoint Online global setting)
In the left pane, select sharing.
Under Default link type choose the option you want to show by default when a user gets a link.
Under Default link permission choose whether you want the default permission to be view or edit.
Change the default link type (site collection setting)
In the left pane, select site collections.
Select the site collection that you want to change, and then select Sharing.
Under Default link type, clear the Respect default organization setting check box, and then choose the option you want to show by default when a user gets a link.
Under Default link permission, clear the Respect default organization setting check box, and then choose whether you want the default permission to be view or edit.