It varies by nation and vaccine-status if it's Covid-relatd, so you have to check the rules for where you're going from, any nation you pass on the way and your destination. They've ease off in lots of places, but moronic mandates may return whenever someone in authority wants it too. Otherwise, main thing you may get hassled on here if you're a dissident targeted for Zersetzung is stuff creating problems for you, like customs insisting on doing a detailed full search of your car, making you miss your plane or ferry. Permits to being renewed for no reason. Tax audits. That kind of stuff.