Hi so I’m a senior who started Cross Country this year ( first year) and plans on doing track ( or soccer) next semester, however, I want to know if it is possible to walk on a college cross country( or track/soccer) team? I’m applying to one D3 school, one D2 school, and the rest are all D1 schools ( University of Oklahoma,U Alabama, U Arkansas, and UF aka my reach school). I do love the sport but I have no information about walk ons for these sports and would love some feedback! Thanks 
If you haven’t already, I would suggest checking out the websites for the sports you are interested in at the schools you are considering. There is often a recruit/walk on questionnaire that you can fill out to get more information. In addition, many current team rosters have bios of the athletes that include their high school athletic achievements. Reviewing these may give you an idea of the caliber of athletes the schools are looking for. Good luck!
While it is possible to be a walk on for track, it is highly unlikely that it will happen for any of the D1 programs you have listed. I don’t know about soccer, but unless you are an extremely gifted athlete it is unlikely that you will be at the level of competition that is typical for the D1s you have listed if you aren’t near that level now. There will be recruited athletes at many of those schools competing for roster spots, as they are hard to come by, and not a guarantee even for returning athletes. Most of the schools you have listed recruit not only in the US, but internationally to field their teams.
Having said that though, if you are interested and think you can hold your own competitively, and are not seeking any athletic scholarship or admissions support, you will need to contact the coaches at each of the schools after you are admitted and find out when they hold tryouts. Some schools put tryout dates on their athletic sites and some don’t. Either way you won’t get much advance notice and will need to get a physical and be cleared ahead of time to participate and should arrive on campus in shape. In the case of cross country, you might even need to arrange to be on campus earlier than the rest of the student body to be part of the try out period.
At my son’s D1 school (which is not in a conference as strong as the schools you have listed) they have a two week tryout period at the start of cross country and track seasons respectively and do take one or two athletes each year from walk-ons. However, these athletes for the most part don’t travel and are used to fill gaps in relay teams, or serve as alternates for cross country, since lots of kids get injured during the year.