I have skepticism about some of your assumptions.
Why do you think Trump would support Russia? I could see it if you believed Trump would remove any tine vestiges of support we've provided to Ukraine, but actually switching sides to support one of the US's largest and longest-lasting threats is extremely far-fetched.
Why do you think Trump would bomb Mexico - an ally? Let alone any South American countries with which we are not currently at war, nor engaged in substantial conflict? And why do you think congress would support it, and why would the US military follow such a clearly unconstitutional order?
Why do you think Trump would ignore China's aggression toward Taiwan, given that Trump has been the only president in my memory to literally recognize Taiwan as an independent entity, and to actually place significant tariffs and trade consequences on China?
I get that Trump is a wild card, and I wouldn't be surprised to see them engage in some crazy aggressions... but the ones you've selected seem extremely unlikely. Do you think Trump is actually The Joker, wanting to watch the world burn? Because "literal crazy person who genuinely wants to genocide the entire human species" is about the only explanation for the items you chose.
What I think Trump would be likely to do is
1) to massively increase US engagement as an ally to Ukraine, disregarding the consequences of that to our NATO Allies, and increasing Russian aggression in response - possibly pulling in China as a semi-ally of Russia
2) Drone assassinate military generals (even if they're "rebels) and heads of state for many Middle Eastern countries, including Syria, Yemen, and Iran
3) Actively engage against Hamas alongside Israel
4) Massively increase border patrol staff, and increase actions against illegal border crossers, and probably just start closing our southern border completely.
All of those come with consequences, many of which are likely to be serious problems for stability in the world... But those are all (imo) more likely given Trump's platform and past actions.
1. What? He certainly hasn't said anything that would reasonably lead to that conclusion.
2. probably more than biden.
3. Maybe, maybe not.
4. He could only do that if congress authorizes the money, there's no reason to believe they will.