XP style TXPManifest is used to enable run-time themes in your application.

 Dialogs, OleCtrls, SHDocVw, StdCtrls, ExtCtrls, XPMan, ComCtrls,MSHTML;
 
   ActiveX;

TXPManifest
Vcl.XPMan.TXPManifest

https://docwiki.embarcadero.com/Libraries/Sydney/en/Vcl.XPMan.TXPManifest

TXPManifest is used to enable run-time themes in your application.

Common Controls and XP Themes

https://docwiki.embarcadero.com/RADStudio/Sydney/en/Common_Controls_and_XP_Themes