Looking at the Attack Bonus, it is possible to see what the highest Ability Score would be.
In the table, the CR is the left column. In the right column, in parentheses, is the Attack Bonus for the monster statblocks in the 2024 Monster Manual, on average, for each CR. Thus the Attack Bonus improves about 0.548 of a point, on average, for each CR. In other words, the Attack Bonus goes up by 1 point about every 2 CR. The Attack Bonus column next to the right, shows this smoothed out progression.
The Proficiency Bonus at each CR is known. Now the Attack Bonus is known. Typically, the Attack Bonus equals Proficiency plus the Ability Bonus. So how high the highest Ability Score tends to be at each CR. For example, at CR 11, the Ability Bonus is +6, thus we can expect to see an Ability Score of about 22 or 23. This is the Ability that the monster is using to make attacks.
The Proficiency Bonus is predetermined according the CR. But the Ability and the Attack Bonus largely depend on the concept of a creature. For example, a Giant will tend to have an unusually high Strength ability, thus also a high Attack Bonus when making Strength Attacks. Even so, having a general sense of what Ability Scores to expect at each CR helps a DM create or modify a monster.
