Microsoft has removed the setting allowing users to defer feature updates in Windows 10 2004. Microsoft made this change because feature updates are only forcibly installed when they are nearing the end of service. Users can now only defer updates for up to 35 days. For Windows 10 Pro and other enterprise versions, you can still defer updates through Group Policies by launching the Group Policy Editor (gpedit) and go to Computer Configuration > Administrative Templates > Windows Components > Windows. Update > Windows Update for Business > Select when Preview builds and Feature Updates are received.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-removed-the-defer-feature-update-setting-in-windows-10/