This is generally the most cost-effective and hassle-free way to ensure you have access to all the premium content the game has to offer.
The most reliable way to get all DLC is to buy or upgrade to the of the game. Digital storefronts rarely sell the base game and DLC separately anymore. The Deluxe Edition automatically injects all weapons, suits, and the two bonus missions directly into your campaign map. Platform Availability tom clancys splinter cell blacklist all dlcs link
Physical "Ultimate" or "Deluxe" discs are the most reliable option for legacy console players, as the older digital stores have limited support. A Note on Server Changes and Unlocks This is generally the most cost-effective and hassle-free