The whole area is sealed off. Some clothes need to take a test and a test to get them. The way to get them is to go to the operation base to find reward merchants. Some clothes are gold-plated gift packages. The seven clothes you mentioned belong to this clothing bag, which can be obtained directly from the reward merchant. There are also some clothes that can be redeemed with U points on Uplay (right-click the global blockade icon on Uplay, then select "Game Details" in the drop-down menu, and find the "Reward" column in the left menu), and some clothes are free rewards for Ubisoft's 30th anniversary, which can be redeemed on Uplay without consuming U points, but they can also be obtained from reward merchants after redemption.

Reward merchants are located behind the stairs facing the only entrance to the base. After entering the base, you can find the reward merchant through the first main entrance without going up the stairs (if there is an underground world DLC, the reward merchant is next to the entrance of the underground world). After finding the reward merchant, you can interact with it and enter the acquisition page. Select the "Decoration" column on the home page to find all the clothes you have acquired.

(★P.S: You can also get resources such as production materials, phoenix spots, government decrees, target information, dark area keys, medical kits, consumables, etc. redeemed by Uplay on the "Resources" page of reward merchants. )