Transaction can started from init mint transaction and give request to jetton_minter. So, if jetton_wallet doesn't exist jetton_minter create new Syde jetton_wallet. Native wallet can take some tons who can exist in mint transaction. If tons enough transaction successfully finish and give your synths. If tons not enough transaction bounced and tons give sender back.
This scheme describes about mint body in process transaction. And we have example from transaction scanner:
Transaction can started from init burn transaction and give request to jetton_minter. Next step is checking exist of jetton_wallet. Native wallet can take some tons who can exist in burn transaction. If tons and synth enough transaction successfully finish and give your ton's. If tons not enough transaction bounced and synth give sender back.