I have had this problem previously and have spent hours on google trying to figure it out. Unfortunately most problems don't seem to match mine exactly.
So I'm doing a udemy course and the instructor tells us to center our view to the big toe of the model by pressing Numpad (.)(/Del). I understand this concept to mean that the viewport uses whatever you selected as a pivot point. Unfortunately the instructor fails to mention how to escape this mode, instead moving into the next video having done it himself but not explaining to the students. I am pissed to say the least
So I tried pressing Numpad (.) on the whole object, in object mode. This helped a little, but I still can't zoom into the feet properly. Before doing all of this, I could zoom into any part of the model just fine. I get that I could change the origin of the model and it would help, but I find it ridiculous that blender wouldn't be able to zoom the length of a human model - I hope that isn't the case and I'm just missing something.
Another article online mentioned that Numpad (/) fixes the issue, it does give the illusion of it being fixed but also hides all of the other objects
Shift (C) is another suggested solution, nope.
Orthographic view seems to help, but I can't use it for many of my projects as I can't see things properly.
This link is to a video example of my issue. When the camera slows, I am still rolling the mousewheel as fast as I can. I also try zooming back out, but am just as stuck.