I don't know about you but when I first tried to write my own adventures as a Dungeon Master for D&D 3.5 I thought I needed a world map. The same was true when I tried my hand at GURPS.
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But what if I told you that that may be the worst way to start a campaign?
Instead, just draw what is needed.
If starting at first level or low level or local adventure just start out with everything they may possibly encounter at those levels.
So if you need a map it doesn't have to be more than 3 days journey in any direction and contain things like "abandoned mine" or "woods" or "larger town will name later."
So don't feel like you have to design the entire world and then drill down because frankly after reading a ton of fantasy novels we feel like that is a requirement, but for gaming you can go the other way.