RPI has gotten more selective since my son applied. He was in the top 1% of his class and according to our school’s Naviance data no one with his stats had ever been rejected. He was accepted early via a priority application they sent him (not ED) and got offered a presidential scholarship there, so our assessment was correct. But for many students the smaller tech colleges will provide top notch academics, but will be much easier to get into than the big names.
My point is you can’t recommend safeties without knowing what you valued about the colleges on your original list. Most safeties will be some kind of compromise Often you can find a terrific department but housed is a school that is too male, or single sex, or too rural, or too urban, or too big or too small.
USC (CA) has a very low acceptance rate. I don’t know what “add interest” means either. My younger son left one LAC on his list in case come April he decided he didn’t want a medium sized research university after all. By April, it looked even smaller to him than it had the previous year when he first visited.