Piece of advice:
Firstly, keep an eye on the status of mountain passes by using for example this website (it's in German but easy to understand; use Google Translate in case of doubt):
https://www.alpen-journal.de/alpenpaesse
Secondly, if you're inexperienced regarding mountain driving, try to limit trips to 7 hours of driving estimated on paper. In reality it's more time because of stops for food, fuel and pictures. Most start to struggle with focus and fatigue around 7 hours of mountain driving. Don't underestimate the differences in height, speed, turning, weather (sun heat) and - most of all - the road conditions and driving circumstances challenging your concentration and stamina/endurance. Personally, I can drive up to 12 consecutive hours in the mountains (actually, sunset is my reference point for ending a day trip - darkness quickly kicks in after sunset).
Last but not least, keep it safe. Mountain driving is an exercise in self-control and concentration. It ain't no game, competition or race. Mistakes can cost you dearly. Happy motoring !