The match between Manchester City and RB Leipzig in Group G is sure to be an exciting one. Manchester City's unbeaten record in the Champions League so far and their previous win against RB Leipzig certainly gives them a strong advantage. Despite already booking their place in the knockout rounds, both teams will be looking to build momentum with strong performances. However, RB Leipzig will be keen to acquit themselves and will likely put up a strong fight. A 4-1 win for Manchester City is certainly a bold prediction, but given their current form and performance in the Champions League, it's not entirely impossible.
Both teams happens to be very rough teams and I except a tough game from them, although like you rightly said Manchester city has already booked their spot in the next round of the champions league but then they still have to play against Leipzig as one of their group stage game's.
Leipzig has been doing well in their domestic league which happens to be the bundesliga and aswell in the champions league, so far they have lost only one game and won the other three from the four champions league games they have played so far, most likely they will be able to secure a spot for themselves at the round of sixteen in the champions league I just hope Manchester city gives them three point from this match so their qualifications becomes sure.