The Sorcerer can get the Metamagic, Extended Spell.
Extended Spell (PHB p. 102)
When you Cast a Spell that has a Duration of 1 minute or longer, you can spend 1 sorcery point to double its Duration, to a maximum Duration of 24 hours.
Delayed Blast Fireball (PHB p. 230-231)
...The spell's base damage is 12d6. If at the end of your turn the bead has not yet detonated, the damage increases by 1d6...
Extended Spell would extend the spell duration to up to 2 minutes. This would add a possible ten more rounds which would be 10d6 damage.
Is this possible for only 1 sorcery point? This would make the damage from a full duration delayed blast fireball 32d6 (192) or an average of 112 damage.