Is 0.002%  precision or accuracy over all temperature range?

20±20 ℃

I think the 0.002% is an accuracy specification at 20℃, but not precision. 

Precision: Closeness of agreement between independent measurements under stipulated conditions.

Accuracy: Closeness of agreement between a measurement result and the true value.

Such as DVM 34401: 

You can find the accuracy  spec at 23℃. And it have another spec "Temperature Coefficient/℃" over all temperature range.

So I think AD8421 can satisfy the requirement from you.