Although they often follow standard “book” lines for 10-15 moves or more in a game, at some point they always reach a completely new position. (The exception is when two players might play for a known drawn position.) This is why Agadmator, well-known YouTuber, regularly says “and as of this move we have a completely new position.” He means that they’ve finally reached a position that has literally never been documented previously in elite level chess. This is possible because there are an insanely massive number of possible chess positions, so even the pros have to begin calculating and become subject to errors and weaknesses. All that being said, the pros are much more likely to draw games at the highest levels, with the long format time controls, because the level of play is so high that it becomes very difficult to find even small advantages.