I haven't tried this yet, but find these lines in CAPITALSHIP_TECHCARRIER.entity

CommandPoints
 StartValue 3.250000
 ValueIncreasePerLevel 0.550000

The StartValue is how many squads you start out with at level 1 - and it rounds down. The ValueIncreasePerLevel is the rate at which new squads are added as the ship levels up. So for this example: level 1= 3.25 = 3 squads ; level 2 = 3.8 = 3 squads ; level 3 = 4.35 = 4 squads ; etc.

Alternately, you could use an ability to add extra squads. If you look at BuffPsiCommand.entity from the AbilityPsiCommand.entity (the Adept Drone Anima ability that adds extra squads to the Halcyon Carrier), it has this entityModifier:

numEntityModifiers 1
entityModifier
 buffEntityModifierType "BonusMaxSquads"
 value
  Level:0 1.000000
  Level:1 2.000000
  Level:2 3.000000

researchModifier
 modifierType "HangarFightersPerSquadAdjustment"
 baseValue 0.000000
 perLevelValue 1.000000

 You can have up to 4 different types of squads on each ship/unit

Hope this helps!

If you want to change the number of squadrons a frigate can carry, or the type of squadron, then open the text file for that carrier and find these lines:

squadTypeEntityDef:0 "SquadTechCombat"
squadAntiMatterCost:0 90.000000
squadTypeEntityDef:1 "SquadTechBomber"
squadAntiMatterCost:1 150.000000
squadTypeEntityDef:2 ""
squadAntiMatterCost:2 0.000000
squadTypeEntityDef:3 ""
squadAntiMatterCost:3 0.000000
maxNumCommandPoints 2

If, on the other hand, you want to alter the base number of fighters per squad, then open the file called "SquadTechCombat" (replace tech with Psi for advent or phase for vasari, and replace combat with bomber for bombers) and find these lines:

scuttleTime 10.000000
fighterConstructionTime 22.000000
decayWithoutOwnerRate 0.010000
baseMaxNumFighters 6

In both instances, you want the last line of the sequence.  Incidentally, if you want to change the individual values for the indif=vidual fighters (damage, armor, etc) then find the filethat looks like "FighterPhaseBomber" or "FighterPsiCombat" and change the values in the pertinent lines.

Almost ?  Sorry, I have a tendency to unwittingly get sidetracked with absurd levels of detail, as I like to think that too much information is preferable to too little...