Object literal may only specify known properties, and 'buttons' does not exist in type 'Settings

Just make sure the dtOptions is declared as any.

You can find this comment on: https://l-lin.github.io/angular-datatables/#/extensions/buttons

// Must be declared as "any", not as "DataTables.Settings"
dtOptions: any = {};

If the Type Settings has been defined by you or your team, you must add the buttons property as:

buttons: any[];

Or

buttons?: any[];

To keep retro-compatibilty.

If the type buttons has been defined by a third part library, instead, there's something wrong in the way you're using it and you should check the documentation to fix it.