What happens when you disconnect the autopilot?
I guess this depends on the AP system and can vary a great deal.
My question would have been " Can the manual trim settings be changed with the AP engaged ?"
If so; disconnecting the AP in flight may cause minor to major changes in attitude, depending on trim settings.
If not, there should be only minor attitude changes initially.
A great deal also depends on the natural design in flight stability of the aircraft and the C/G
In any case, pilots should be "hands on" when changing the AP setting
just in case something has, nevertheless, hit the fan !.