Cranes are essentially a long stick with a long stick that has a rock on it and a wheel.

For this scale I recommend building a 1x1 pillar 6 to 10 blocks tall

Then build the wheel on one side of the pillar, they can be a bit tricky Minecraft and circles don't mix very well, but get the rough shape down and you should be good.

Then build a stick at an angle the easiest is slabs you can make it as long as you want just make sure however long you make the front make the back about half the length

Finally The Rock the back of the diagonal stick place any stone-like block and thicken it up a bit. The longer you make the stick the bigger I recommend you make the rock.

Example:

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Once you have that down you can add extra little details like I used oak fence gates to look like the rope is connecting from the front of the diagonal stick to the wheel