Forced Moves

When my opponent has a forced move or a series of forced moves.

Is there anyway to force those moves on my own.

Or announce mate in 7 for instance?

No there is not. I suggest writing them in your notebook so you don't have to reanalyze the game every time they do move. You could also message your opponent along with the move giving your analysis and hoping they will resign. However, if your analysis is wrong...