Man City players will definitely not underestimate Inter Milan. It's just that Man City, who might be playing more carefully, could actually be used by Inter Milan. Man City, which always fits their attack strategy, will certainly trouble Inter Milan's defense. But if it turns out that Man City has reduced the aggressiveness of their attacks, then this will open up opportunities for Inter Milan to be able to turn around to play more attacking. But Inter Milan must also be aware that Man City players' attacks are always dangerous. so Inter Milan might choose to use a defensive strategy in the final match later.
The final match is only one, not like the other matches where there are first and second leg, so I don't think Manchester City will underestimate Inter. They will try to attack and score few goals to secure their position, after that there's a possibility Manchester City will underestimate Inter because they don't need to play very well anymore.
Inzaghi don't have any special strategy, he always use a classic balance strategy 3-5-2, Guardiola definitely know Inter's strategy and easier to find the weakness.