Will the world be more or less peaceful with Trump in power?

[Pemalite]

Nothing will change.
Trump like all presidents are more or less beholden to what congress pushes and the politics on the world stage.

The fear that any president will "destroy America" is pretty baseless, that claim has been thrown around for centuries, it's simply politics.
Plus Trump doesn't have a good track record, he couldn't even build a wall to keep illegal immigrants out during his term like he promised, yet blamed illegal immigrants on the Democrats. - If Trump did his job it would be a non-issue to start with.

And whatever big policies Trump pushes during his term, will just get undone with the next democrat who comes to power if it doesn't work. See: Obama care.

In saying that, I am going to enjoy the drama that comes out of the Trump administration, the last time he was in power it was great and free entertainment, the world took the USA less seriously, but it definitely was good entertainment.