What is the magnetic flow meter electrodes resistance range, specially for 2 inch size

You can't find a specification value for a magmeter's electrode resistance because no one cares what that value is except the manufacturer's electronics designer.

What are you really asking about? The minimum conductivity of the liquid in the magmeter tube? That's a number spec'd by the manufacturer on the spec sheet.

Or some other value?
Magflow meters rely on flowing conductive fluid. The current flow is minimal so unless you have a non-conductive buildup on the electrodes, you'll get a reading. There are a variety of insitu electrode cleaners.