Yes and No. Rings of Spell-Storing and the Artificer's Spell-Storing Items are different.
The Spell-Storing Ring is a specific magic item, whose text says the following:
Any creature can cast a spell of 1st through 5th level into the ring by touching the ring as the spell is cast. The spell has no effect, other than to be stored in the ring. If the ring can't hold the spell, the spell is expended without effect. The level of the slot used to cast the spell determines how much space it uses.
While wearing this ring, you can cast any spell stored in it. The spell uses the slot level, spell save DC, spell attack bonus, and spellcasting ability of the original caster
Since the spells are cast to store them in the ring, it would be possible to cast these spells using higher-level spell slots. When you do so, the spell would be treated as a spell of the same level of the spell slot expended; if you cast Magic Missile into the ring with a second level spell slot, it would be a second level spell, take up two levels of space within the ring, and produce an effect as though it was cast with a second-level spell slot.
However, by contrast, an Artificer's Spell-Storing Item, despite having a similar name, works entirely differently:
Whenever you finish a long rest, you can touch one simple or martial weapon or one item that you can use as a spellcasting focus, and you store a spell in it, choosing a 1st- or 2nd-level spell from the artificer spell list that requires 1 action to cast (you needn't have it prepared).
No spell slots are expended; when you produce a Spell-Storing Item that contains Magic Missile, you can't expend a second-level slot to make it fire an additional missile - and Magic Missile is only a second-level spell when cast from a second-level spell slot.