I have 80 feet from the meter disconnect to the breaker box inside the house. I am running it underground with 2" pvc conduit and I need to know how to size the wire for 100 amp service. Thank you

For this , # 2 aluminum or , better, #1/0 aluminum 4 wire URD cable is available. I would run #4/0 to be ready for upgrade to 200 amp. Cost is probably comparable due to popularity.