Im a senior in high school and my PR for the 5k is 21:30, for this upcoming xc season I wanna make a drastic improvement since its my last year, whit running 60 mpw over the next 14 weeks what times could i realistically expect, ive only been running for 10 months and my pr was on 30 mpw
Make sure you know what you are doing and don't hurt yourself. My advice would be to also not set too high of expectations. It could get discouraging if you have a huge goal like 18 flat and don't see yourself getting close.
In your position I would focus on getting comfortable moving faster. If you really want to run 18:00, a 7:30 mile should feel easy (you could do all of your weekly mileage at that pace without feeling tired) and you should be able to do a 20 min tempo run faster that 7:00 pace.
I don't mean to discourage you from your goals, but just know that dropping 3:30 would be a crazy season. The biggest improvement I have seen recently (from someone who was not new to the sport) is a 20:30 turning into an 18:40. Realistically going sub 20 would be a fantastic single season improvement for a 21:30 runner. I am confident you could do this or more by making the transition to higher mileage - as long as you make the miles "good" miles in that you keep them at a good pace. I would aim for between 8:45 and 9:00 for easy days and pick it up as you get stronger.
Good Luck!