There are plenty of ways, which Trump is actually doing, to handle the criminal elements of immigrants and also getting rid of various visa exemptions that was implemented during the Biden administration. However, one cannot get rid of people of different viewpoints and religions without violating the Constitution.
As far as problems abroad, not our problem unless it impacts the USA now or in the future. We already learned from past experience in recent history that nation building does not work unless the educational infrastructure is there. Can't teach people with 13th century mentality today's concepts. Reason we are involved with Ukraine and various countries in the Middle East is due to our strategic interests. Sudan or Congo not so much. That's the reality, now find some rare earth minerals, abundant water or oil there, they'll be our best friend.