Apple warranty

Apple’s international warranty is explicit in that it can only provide cover/support available in the country in which the claim is made - and that this will not necessarily be equivalent to that of the country of purchase. 

Ideally you will claim in the country of purchase - or if travelling, will wait until you return to seek repair or make a warranty claim. The international warranty provides an additional (if limited) safety net.

However, as both countries you mention are within the European Union, your Apple warranty is valid and will be honoured in any European Member State. As such, if purchased in Germany, your Apple Warranty will be honoured anywhere within the EU.

No, you cannot assume that the warranty will be honored in another country. You can read for yourself here.

Legal - iOS Warranty Document Us - Apple

IMPORTANT RESTRICTION FOR iPHONE, iPAD, APPLE TV and HOMEPOD SERVICE.

Apple may restrict warranty service for iPhone, iPad, Apple TV and HomePod to the country where Apple or its Authorized Distributors originally sold the device.