The teachers who are writing the LoRs only write one for you, one that isn’t specific to any college.
Yes, in the common app, you can select which LoRs you want to go to which colleges. Remember to get two LoRs from core subject teachers, although some schools may only accept one LoR.
ETA: Here is the common app FAQ on LoRs. What you do at your HS may be different if you use Naviance or Scoir, so talk to your GC. Remember to use the common app FAQs for your questions, the information is a helpful resource.
https://appsupport.commonapp.org/applicantsupport/s/article/How-do-I-assign-my-recommenders