In July 2021, the German border guard (
Frankfurt airport, on the way to Santiago) asked me where I was going, for how long, did I have enough money, and did I have a return ticket. He let me off on that last as I fumbled through my phone.
Their concern is that you have enough money to leave, and that you * will* leave before your 90 day limit.
While many on the boards will tell you, quite rightly, that they were never asked these questions, the fact remains that the border guards are permitted by law to ask for proof that you will not claim asylum in their country.
Basically, have at least a credit card, a rough itinerary, and a planned departure date handy.