I think Trump might be right (even using his twisted logic) that if he was still President that the Ukraine war would never have started last year, though not for the reasons that he would have us believe.
Putin would have had his lackey still in the White House and therefore, as John Bolton stated, Trump would have weakened NATO so much so and even tried to disband it that Putin might not have felt the need to invade Ukraine as there would be no chance of Ukraine, a country on Russia's border and with close ties to it, ever joining NATO.
Though following that train of thought, if NATO was disbanded as Trump wanted, then Putin would have probably tried to undo another wrong that he spoke of and subsume the Baltic countries back into the Russian orbit by any means necessary. Then why stop at the Baltics, what about those other Slavic countries, surely they would be better off taking their lead from Russia as it was in the good old days? After all, Putin must "MAKE RUSSIA GREAT AGAIN!"
I strongly doubt the world and particularly the European outlook would be as bright as Trump makes out if he was still President or god forbid, he becomes President again.