On top of all the comments that other made here, it also depends of the high school.
So, for example, when my kid was applying, UMN (OOS) had an acceptance rate of 45%. However, according to the school’s Naviance, UMN had not rejected any students with stats anywhere close to those of my kid, at least for the previous 3 years. However, there were a bunch of colleges with similar acceptance rates which rejected a large number of students with similar stats.
So a college with a 40%-45% acceptance rate, at which an applicants is in the top 25% of previously accepted students, can be a match, but can also be a safety.
Also, colleges can suddenly decide that they want to increase selectivity of OOS students, and a college which were a safety one year, can no longer be a safety the next year.
The larger the number of applicants to a college, relative to the number it can accept, the less weight stats will have, compared to other factors. Once a private college has an acceptance rate of about 35% or lower, stats alone can no longer ensure admission. Since all other factors are much more subjective and the competitiveness of any changes from year to you, that is around the “selectivity” level at which a college cannot be a safety for anybody. Even very selective public universities often have auto-admits based on various criteria, so they may be safeties as lower acceptance rates.
So an applicant with a 3.87 GPA and a 1580 SAT and strong ECs and a good essay and LoRs would be competitive for any of the Ivies, but still has enough of a chance to be rejected from, say, Villanova, that it could not be considered a safety.
Furthermore, many of the things that can make an applicant attractive to Harvard, would not have the same effect on Villanova, for example, being a legacy for Harvard. Geographic location, minority status, etc, all affect an applicants chances differently at an Ivy than at, other colleges.
Which brings us back to the concept of an “Ivy-league level applicant”. Would one consider the effects of “hooks” when describing somebody as “Ivy-level”? What about the fact that an applicant has become famous for something? Ivies often love having these students, but many other colleges are less enthusiastic.