I lived in two state in 2021. I contributed to 529 in Dec 2021. Can I claim deduction from first state income tax based on proportion of residency?

What are the two states?  Was the 529 a state sponsored plan? Most likely, you deduct the whole amount for the state you lived in when you made the contribution or the state that sponsored the plan.  

It depends on the details .

I lived first 9 months in MO and last 3 months in CA. I contributed to NJ best plan in In Dec during CA residency. MO allows that deduction but CA do not. Can I take that whole 16K deduction from MO?

No, you can only take the deduction for the contributions made during the time you lived in MO on the MO return.