Hey welcome ^_^
Ive been on nearing 2 years and still going with this sim, some have been here way longer so you know it can be pretty worth it.
Some of us started out with no knowledge and now control in expert server, some of us came in as real life pilots or controllers and have shared valuable information on tutorials as mentioned by everyone.
If you really want to learn something, as any humble person, you can go a long way here. Once you get used to the offline solo mode, i would suggest not buying any planes during these process, the free planes are very helpful for a ‘trial’ of the many other planes.
Instead invest about $6 for 1 month of live, use that time to experience casual and possibly training server. You may find southern california to be irritable at the beginning if you are really serious or more of a perfectionist so i suggest other free regions.
If you enjoyed the 1 month, you can consider saving for a $60 1 year subscription with all planes and regions loan to you during this 1 year. Try to hit expert server and experience the ATC services and pilots who know what they are doing, of course, only do this when you are ready or risk getting kicked and reduced grade.
I know this is more than you asked but it will be worth knowing alittle more xD considering you did mention IAPs too.