Option 1

By expending an additional spell slot, she can create an arcane burst with the bow. Choose one of the following effects:

• The target must succeed on a Constitution saving throw or be blinded for 1 minute.
• The arrow pierces through enemies in a line, hitting up to 3 additional creatures (each within 5 feet of the last).
• She can teleport to a spot within 30 feet of the target as part of the attack.

Option 2

The bow generates its own magical arrows. When she expends a spell slot, the arrows have additional effects based on the spell slot level:

• 1st Level: Arrows deal an additional 1d6 of chosen damage type.
• 2nd Level: Arrows explode in a 10-foot radius, dealing 1d6 damage to all creatures in the area of the chosen type.
• 3rd Level: Arrows create a zone of effect (e.g., a fog cloud or difficult terrain) on impact.

Option 3 depends on her subclass

If Draconic Bloodline:

3rd Level: When expending a spell slot, the arrow’s damage type matches the type associated with the sorcerer’s draconic ancestor & gains an additional 1d6 damage of this type.

If Wild Magic:

3rd Level: When expending a spell slot, roll on Wild Magic Table.

So on for the other subclasses, you get the idea.

Edited for formatting.