I went to a fairly competitive D3 school about a decade ago (made Baby Nats 2 of the 4 years I was there), the cuts were done based off a 5000m Time Trial run on the 2nd or 3rd day of XC practice. Time target was 16:40 to make the team (they changed it one year to be 17:10ish or so, forget the exact time, after a big class of seniors graduated to allow on more Freshman than usual), with a little wiggle room for kids with faster HS PRs who might have bombed the TT (for whatever reason).
Guys with slower PRs would try out each year (coach encouraged everybody who was interested to come to the TT and try out) but the time cut was strict unless you had 4:30ish or better 1600m/mile PR from HS. Showing up to college and hitting a 16:3x 5k off summer training is tough, guys with HS Track PRs in that ballpark (4:50 milers / 10:20 2 milers) pretty much were never able to hit it, and they were told to come back next year if they still wanted to compete (to the credit of a few of them some actually succeeded their Sophomore year). Generally unless you had a 4:40 low or better in High School kids didn't make it.
Roster size was generally around 15-20 guys on the XC team in any given season.
Women's team was (practically) no-cut by comparison & much larger, presumably for Title IX reasons.
I can't speak to the specific programs you're interested in, but I would reckon most competitive D3 programs have similar benchmarks, where being a sub 4:40 miler is probably the indicator that you'll likely make it. I will say though - some programs, even very good ones, I believe are no-cut (or nearly no cut) when we talk about the D3 level. Depending on the sports the college offers they may ore may not be able to offer a lot of extra roster spots to men on XC/track. If you check their present roster size it might give you some indication.