Constant whining

I think I’d play it off as if she’s talking. Like, respond to it as if she were saying words. “Yeah, you’re right! I see that (characters in the book are doing xyz)!” I don’t know how old your little one is, but I think because she isn’t verbal yet, I’d consider this a form of communication and encourage it as that leads to more development of skill and could lead to verbal communication

How old is she? It’s a little tough if she’s not talking and just making noises. If she is just having an off moment here or there I comfort but if it’s a habit it’s fair to address it. When my daughter whines I have always told her calmly and nicely “oops, that’s not how we communicate! We don’t whine, we ask for it like this..” and then model how to communicate without whining. That has always worked well but she has been talking well since before she was 2. She just turned 5 and up til now hasn’t done a ton of whining but is currently in a whining phase and I am reminding her a lot through the day at the moment that we don’t whine to communicate. I also sometimes tell her it bothers my ears listening to those noises, if you just feel like you want to whine you can go in the other room lol

Is it just really recently? Since she’s not talking I’d wonder if it’s just something she’s learned to do so she’s doing it a lot. In which case I’d say she’ll stop on her own and move on to something else.