Intercontinental (IHG Reward) and Venetian/Palazzo (Grazie)
 

Since Intercontinental and Venetian have partnership going on, if I have Platinum IHG status, can I enjoy the benefit of the Grazie Platinum benefits?

Grazie is a players card

i thought it's a loyalty program where you can enjoy benefits based on the tiers and earn points by spending money there.

You don't get grazie benefits when staying as an ambassador/RA you do get the defined ambassador benefits. Since these properties are IC affiliates only ambassadors and above should be entitled to benefits.

You can run your grazie account in parallel with your IHG account here though.

This property only offers 2k Points per stay credit so you can credit all your on property spend to grazie since you get no credit to your IHG account for spend.