Trump doesn’t usually like to get too far in front of the base, but there is one exception: Russia. He really, really admires Vladimir Putin. And so, assuming the Ukraine conflict is still going on in some form, you can expect him to change sides and try to impose an unfavorable peace–possibly even surrender–on the Ukrainians. He would justify this to the base and the rest of the nation by arguing that it would reduce oil prices and help us contain China, the real enemy.
Given the genuine strength of pro-Ukrainian feeling within the GOP, would he get away with this? History says yes. Nobody–not even the ultra-hawkish Lindsey Graham–was willing to stand up to him the first time around, so why would it be any different now?