This is something that has been "bugging" me for a long time. I've been reading about Osrams tactics, and there is no consent about this, except that everyone agrees he has been heavily manipulating his approach based on opponent.
However, most agree about a few things. He used a defensive forward to put pressure on dlps, drop deep and squish play. He played a high defensive line for the same reason. He used teamwork heavily along with a very fluid approach. In most games, he used the right flank as the favorite outlet. He used high pressing.
In some games he used a 4-2-3-1 wide with counter attacking approach, not being fussed about possession, and using a tremendous tempo. But, after a few goals lead, he would drop to 4-2-3-1 deep, retain possession, and lower tempo, a tempo even slower then barcas tiki taka.
His players are physical, not technical, and he used their height and weight to bully the opposition. His right fullback is dual footed, and he gave him freedom to do both cutting in, running wide, dribbling, shooting or passing. Defenders would usually back off, as they felt they couldn't commit. Left fullback is also given a lot of freedom, except cuting in, as he is not dual footed. His right flank is usually the one starting the attack, but, again depending on opponent, he used the left flank. Never both.
As I only have demo, and there is no Germany available in it, I couldn't chose Bayern to test my tactics, and the tactics depends on his players, and is tailored for his team, so I offer no screenshots, and I hope you will forgive me. But, in case you are playing with Bayern, feel free to test these two, and if possible, give feedback.