In GTA 6, the map shows the loot hidden in each gang hideout: how much cash and how many drugs are inside. You pick your target before you even leave. According to RoddyGames' video, which cites Rob Nelson speaking to Famitsu, the process works like this:
1. Find the hideout holding the most cash on the map.
2. Sneak inside quietly.
3. Grab the cash.
4. Send the drugs to a fence to sell them.
The same source says the missions alone won't pay for the story, and these hideout jobs are how you keep the game moving forward.

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