Is en-passant forced


No.
It is optional.
3.7.1 | The pawn may move forward to the square immediately in front of it on the same file, provided that this square is unoccupied, or |
3.7.2 | on its first move the pawn may move as in 3.7.1 or alternatively it may advance two squares along the same file, provided that both squares are unoccupied, or |
3.7.3 |
the pawn may move to a square occupied by an opponent’s piece diagonally in front of it on an adjacent file, capturing that piece. Notice the word may frequently appears as opposed to the word must.
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