About Washington State estate tax return with 529 college fund

Hi,

How are you?  Thanks for your help

Washington state has $2.193M estate tax exemption in 2024.  Let's make it easy for me to explain my question.  Say Washington state estate tax exemption is $2M rather than $2.193M.   

Hypothetically, say I contribute $600,000 to my 3 grandkids 529 college fund.  I also have real estate $700,000 and financial investment & retirement $1.4M.   Add it up, I leave behind $2.7M if I die suddenly.

In that scenario, do I pay estate tax based on the $700,000 which exceeds $2M or I just need to pay estate tax based on the $100,000?   

In other words, can 529 college fund be excluded from my net worth since it is contribution or gift?  If not, would it be better off I give them tax-free annual gift ($18K) to reduce my net worth over time.   

Please shed light for me.  Thank you for your knowledge.