Some more unreleased TROS concept art by Kevin Jenkins on Twitter:
Palpatine :
https://pbs.twimg.com/media/Epd2_JYW4AIItSg?format=jpg&name=medium
Emerging from the ashes of Coruscant:
https://pbs.twimg.com/media/EpjhCJjXUAE1Pgf?format=jpg&name=small