There are a few instances where Shakespeare does explicitly state that a main character will die, but these are typically cases where the character's death is not a surprise. For example, in Romeo and Juliet, Shakespeare makes it clear from the beginning that both Romeo and Juliet will die. However, he does not reveal exactly how or when they will die, which creates suspense and intrigue.
In general, Shakespeare uses a variety of techniques to create suspense in his plays, and eliminating suspense by telling the audience that main characters will die is not one of his common practices.