What is perfect play? What exactly is perfect play? Can there can be multiple perfect plays, which sounds quite contradictory? If perfect play is known for all openings then why would a player play anything other than that?  Such a thing would make all high level games futile because then players would intentionally divert from perfect play in order to just create a show or something similar.
In the context of game theory, perfect play involves playing truly optimal moves.  Specifically, if the game state is a (theoretical) win for the player to move, perfect play would be a move that both preserves that state (eg keeps the game a winning state) and minimizes the number of moves remaining until victory.  If the game state is a draw, perfect play preserves the draw.  If the game state is a loss, perfect play cannot improve the theoretical outcome, but instead maximizes the number of moves until defeat.
Perfect play is, by definition, known for solved games like Tic-Tac-Toe.  Chess is not yet solved, so in most board positions, perfect play is not known.  For some situations, for example positions with 7 or fewer total pieces on the board, we have endgame tablebases which have perfect play recorded.  Also, for positions with forced checkmate in sufficiently few moves, engines can calculate perfect play on-the-fly by simply looking at all possible moves and responses and choosing one that gives checkmate the fastest.  Perfect play is not (yet) known for chess openings.  If chess were solved and perfect play were widely known, then it is possible competitive chess may die.
There can be multiple perfect moves for a given board position.  For example, if there are two different moves that immediately checkmate the opponent, both are perfect.  Playing around with endgame tablebases, it is fairly common to find positions where multiple moves lead to checkmate in (say) 18 moves.  If the game is a theoretical draw, often many moves preserve the draw.  All of these moves are perfect from a game-theory perspective, though some may give better practical chances than others.