You extract them into your image folder for the game. If you are not sure where that is go in-game and select any character and click 'Full body image'. This opens the dialogue for selecting portraits and body images. On the right is a button 'Open system folder'. Clicking that will open the path to where you want to extract those images to.
Default is usually %user/appdata/Roaming/Strive
P.S. Each part should have their own sub-foolder there btw. So portraits go into a portrait folder and body stuff into a body subfolder - just in case you dont have those folders. These packages have those folders in the packed version and you need top make sure to extract them accordingly. This is needed if you want the game to be able to match races with images automatically.