SharePoint Online: How to Disable Download Option for Documents?

Requirement: Disable download document options in SharePoint Online.

SharePoint Online: How to Disable Download Document Button?
To restrict download options for documents such as download a copy, download button in SharePoint Online, here are some options:

Option 1: Grant "Restricted View" Permission to Users
To disable download option in SharePoint Online, you can grant the "Restricted View" permission level to either a particular user or group which allows only read but not download.

This applies to a site or document library where you grant permissions. Users with a restricted view get a message "You don't have permission to download or print this file." And SharePoint doesn't allow these users to copy-paste also from Office documents.

Option 2: Share a File with Block Download Option
Unlike sharing a site or document library, You can share a specific document with download option disabled. To share a file,

• Select any office documents, Click on the Share button in the toolbar (or from the context menu)
• In the Share Popup, Click on "People in <Your Domain> with the link" or "Specific People" Option. Uncheck "Allow Editing" and enable "Block Download" option.
• Click on Apply, and enter your recipient name
  

This disables download options. Please note, the block download option works only for Office documents such as Docx, Pptx, Xlsx. For other file types like pdf, png, etc, you won't see the "block download" slider!

This allows SharePoint Online users to view documents while blocking the download.