To answer your original question, I think that As and Bs are just fine for getting in, but you also need to show extracurriculars and transferable skills and all that.
If you're looking to get into Cornell for vet school, and that's why you want to go for undergrad, I agree with everyone else that it doesn't matter where you do your undergraduate studies. I went to Cornell for undergrad and absolutely loved it, but wow is it expensive.
To be thorough, the advantages I could see with going to Cornell for undergrad are: there are a number of classes you can take with vet school faculty, and extracurriculars in which you'll meet and interact with vet school faculty, so you might be able to get a letter for vet school, plus you get to interact with animals and do vet med-related things; the pre-vet advisors for the undergrads are the most familiar with the requirements for CUCVM; it's easy to meet with the vet school admissions people any time; depending on your age and living status, you might be able to get in-state residency during undergrad, after a couple years; CUCVM does give a bit more weight to Cornell undergrad applications ("rigor of academic program", I think they call it), and I think they go a bit easier on us when it comes to evaluating GPA. We had 14 students from Cornell undergrad end up attending the vet school in the class of 2019.
HOWEVER. All those advantages I listed are more like "reasons why current Cornell prevet undergrads should give it a shot and apply to Cornell for vet school" as opposed to "why you need to attend Cornell for undergrad in order to increase your changes of getting into Cornell vet school". You might get a little bit of a boost / convenience with some of the things I listed, but it isn't worth the financial cost; plus a lot of it can be made up for with a little more legwork. Yeah, you'll get a good education at Cornell, but you can get a good education at a lot of places, and vet school basically reteaches you things the way they want you to know them, so a foundation in pre-vet-y courses is helpful but not essential (and you'll all have to do all the same pre-reqs anyway). Honestly, if I had to do it over again, I would go somewhere else for undergrad, because after I graduate vet school I will have been here for 8 years - which is a really long time to be in Ithaca (which is beautiful, but cold, and we don't even have a real mall nearby 🙁).