No manual adjustment I believe it tightens to a fixed spot.
I reckon you need that rubber block at bottom of the door to create the right closed door tension. They can be knocked out easily.
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Whaat...makes no sense at all..how do they adjust when fitting the doors originally?
Maybe like in old days...with a long bar and large hammer 😎
Now I'm going to undo those screws to find out if they move ...but given the modern car is largely un repairable..i suspect you are right!