When it’s time for you to apply for a PhD, you will have a very clear idea of what you want to get a PhD in. If you don’t, you probably won’t pursue it.
Having recently seen first hand the process that someone takes to apply for a PhD, no one would pursue it if they weren’t very serious about the effort it takes to get into a program.
Many people wait a few years out of college before applying to PhD programs. Without ticking several boxes, you’re wasting your time, tbh. I do know a couple of students who were accepted to PhD’s right out of college, but I also know more who applied and never got an interview. One of the latter group applied while a college senior and got no bites. She got a job in something related to her field, worked for a couple of years, and is headed to the top PhD program in the country.
I can say that if it’s in your future, ensure that your experiences leading in to that point are relevant to the PhD you want to pursue. I’m no expert in the process, but I am certain that it’s mostly a case of getting to a point in your life when you realize you have what it takes to be competitive for a PhD.