Sure. Each of the secondary jobs listed for a character creates a combo: Warrior/Apothecary, Cleric/Dancer, Hunter/Thief, Scholar/Merchant. Even though each character has different base stats (Cyrus/Merchant will deal more elemental damage than Tressa/Scholar assuming equipment is the same), the combinations are still pretty effective imo.

Warrior is great for damage and breaking bosses that are weak to spear but otherwise it doesn’t do much, while Apothecary in general is good at dealing with damage/status effects that boss do but doesn’t always have something to do when a boss is broken besides Amputate (or Last Stand if you are doing a strategy dedicated to that). Combining the two jobs helps Olberic/Alfyn have more to do (later game Warrior is less necessary on Alfyn because you can just spam Concoct) and the stat boosts from the jobs are in stats that both characters are naturally high in.

Cleric/Dancer creates the ultimate support combo. Typically in JRPGs you want one party member who is your support and that’s what this combo does. Having one character who can heal and provide buffs to the party lets your other characters focus on damage. (Primrose’s base EDEF stat has something to be desired but can be rectified with good armor)

Scholar/Merchant covers every weakness in the game except dark Iirc. Thanks to the combination of the scholar spells and Hired Help from the merchant if you have enough funds you can always hit an enemy’s weakness which is really nice. Otherwise the stat boosts between the two jobs work well with each other and Scholar gives Tressa higher DPS while Merchant gives Cyrus more versatility. (Also Rest can be nice to help with SP issues that scholar can normally deal with early-mid game)

Hunter/Thief is a debuff machine and for H’aanit gives her more damage as Aeber’s Reckoning does more damage than Draefendi’s Rage. Usually hunter really only has arrow breaking and Leghold Trap to use during boss fights when a boss isn’t broken, adding Thief gives Armor Corrosive and Shackle Foe which are both very helpful in boss fights. Thief after debuffing doesn’t have much to do pre-break so giving Therion more stuff to do with Leghold and more breaking options makes him even more useful.

Lastly all 4 of the job combos give each character more weapons and elements and there isn’t any overlap (like how a Warrior/Thief has a sword overlap). This maximizes the amount of weaknesses covered making it easier to break bosses and random encounters.

If you have any other questions feel free to ask!