Sounds OP is not looking for the technocratic Autobahn of Kraftwerk but more for Ich will Spaß by Markus - an 80s ode to speeding.
Honestly I am not a fan of this because Autobahn is no race track and most tourists do not have the necessary German car driving education / knowledge nor the necessary experience.
70% of German Autobahn do not have speed limits. Although Bavaria is the German state with the most Autobahn kilometers Munich area is seldomly free enough to enjoy Autobahn, especially in summer. In 2024 Germans spend 448,000 hours in traffic jams on Autobahnen, 15% in Bavaria only.
On A9 the chance is likely highest to find a little space to get experience with Autobahn but be aware that this is used by a lot of professional drivers; so it can be also more stressful if you drive in front of impatient people.
Most important: make yourself familiar with all rules incl. physical laws regarding Autobahn rides (2 and 3 lanes). In Germany nobody gets a driving license without a minimum driver training on German Autobahn (minimum 4 hours in total).
I was driving motorways in many countries - in the US I often found low quality of motorway material which is no joy to drive on. In most cases this is enough for what is allowed there but not safe for more extreme conditions. Closest to German Autobahn quality I found the ones in UAE.