Isn't the 20-year plan written into the 2017 Constitution? I think it is, and all Government agencies and public organisations must comply. A committee of senators was given powers to monitor progress and use the NACC to suspend (even jail) anyone who fails to comply.
I can only find a link in English in the Bangkok Post, which we aren't allowed to quote - but googling "20-year national strategy comes into effect" gives more info.