Globalization /makes/has made/made/is making/ the world smaller.
Cheap international flights /make/have made/made/are making/ overseas travel possible for millions of people.
Depending on the context, all of the tenses are possible and could have very similar or very different meanings.
Make/s - most general, less focused on current result or process.
Have/has made - present result of something started in the past
Made - in the past.
Is/are making - focusing on current process.
But from context we often already know the timeline and the results, so there could be multiple options to convey a certain idea - possibly with different emphasis.
In isolation, the first statement is basically meaningless and the second is imprecise to the point of being meaningless. There’ve been millions of travelers for a long time.