realistic goals

Too many variables to say.
Depends on the time you put in and how you use it. Also depends on your natural ability.
Put in an hour to a few hours every day and split the time between playing, reading books, watching videos, doing tactics puzzles etc.
I’d say you will probably reach somewhere between 1000-1500 in 1 year and if you are really gifted, maybe higher.

Hi! My name is Lauren Goodkind and I’m a respected chess coach and chess YouTuber who helps beginners out :
https://www.youtube.com/channel/UCP5SPSG_sWSYPjqJYMNwL_Q
As an experienced chess player, I learned that everybody goes at their own unique pace. For example, there are some people who gained about 1000 points in a year! Don't compare your with others. I think that if you are serious about improving, then I think gaining several hundred points is very reasonable.