Visit the branch of any of the below with your Iqama, or your passport if you don't have one yet:
Besides the major three, there are micro-providers such as Jawwy, Virgin Mobile, etc.
π‘ Tip: Compare the prepaid and postpaid packages as some include free regional calls, roaming etc (for example to Bahrain)Β
Look for a metal plate outside with a STC, Mobily or Zain logo. This means your building is serviced by fiber and you can apply for those packages.
If your building or area is newer and does not have any fiber, you will need to grab a 5G rpackage (router is free if you take a 12 month contract):