Does knowing your opponent's personality have any influence on the game-plan From Reputation and badges should be kept hidden until the question is answered, the below assertion is presented:

It is often asked in chess, that does the personality of the opponent player has any influence on their game plan, the answer is almost yes for all grandmasters. Most also feel uncomfortable playing against Computer as a competitor in chess even if it's radically low-rated running at 1/10th of its strength. Why, because people lose, not because that they are weak players but because of the inherent psychology involved that "computers make no mistakes". On the other hand, low-rated players often lose quickly when they know before-hand that the opponent player is a grandmaster. However, if the opponent rating is unknown, he tends to a better play, and even a long shot at winning it.

Do you agree with the above assertion or did you had any contrary experiences in chess. How do grandmasters employ assessing the personality as a tool to develop their game plan?
You can only adjust your plan to your opponent when you have multiple moves that are equally or almost equally good objectively, since sometimes one of these moves might seem better than the others against a particular opponent. But making an objectively poor move in the hopes that your opponent will not find the refutation is asking for punishment.

By far the primary means of adjusting one's style to one's opponent is selecting the opening. For example, the Sicilian Defense and the French Defense are both good choices objectively, but you might have reason to believe your opponent will perform worse against the Sicilian than the French. But if you know the French better than the Sicilian, you should probably choose the French, or else your choice of opening might hurt you more than your opponent.

This isn't the sort of thing most players really need to worry about until they become quite strong (master level). Usually in a tournament game you should just make the moves you're most comfortable with and play the moves that seem objectively best.