Re: the youtube channels/vids telling you can beat 5k and 10k of 20 mins and 40 mins etc.......of coz they have to sell you (the runner) the dream first, without much assessment of anything.
Coz the majority of these channels offer coaching and sell plans.
Maybe some will be more realistic......ask you adjust your goals and go step by step, but if talking about 30-35 min 5k drop to 22-25 min, it'd be great for many people, the newbie gains are the biggest and that is true for the vast majority of people taking up any sporting activity.
Still, they prob will be trying to dangle the carrot and tell you that "magic" 20 mins is achievable...that's the hard part

It is mostly the process that is fun.
Then for the more "elite", training for sub 18, 17, 16. heh.....that one gonna be hardcore.