I want to buy a plot of Rural zoned land in Clark county and turn it into a parking lot. Can I make a offer and then have the zoning change as part of the contingency during due diligence?
Zoning is going to take way, way longer than any due diligence period you're likely to get.
Yes your offer would be contingent on getting the property rezoned so you will not close until that process is complete as well as all other approvals needed for the use you have in mind not just rezoning.
This is common with land. I never close until I get all entitlements.
The risk is you will need to spend money to get the zoning and other approvals.