Hi,
You requirement is to have Stock transfer Price different for different plants which located in different states
and now you are confusing yourself "Transfer price configuration plays any role?"
Yes, Transfer price configuration plays vital role where freight condition type configuration need to be taken care and later freight condition type addition required in STO Pricing procedure.
Just configure in your system and do transaction process for different plants with different delivery cost , you will know the result at the end!
Regards,
Biju K