The first page (roughly the first 13 lines of the manuscript) should provide the reader with an interesting character/POV and some micro tension from an immediate problem/challenge.

The challenge doesn’t have to have a life-or-death stakes.

In the case of one of my favorite Stephen King openings (The Library Policeman), it was simply a juggler injuring themselves and canceling an event thereby forcing the main character to fill in.

The initial challenge is a chance to hook the reader and get them invested.

If the reader is wondering what will happen next and/or whether the character will solve the issue, they are a lot more likely to read page two.