I used D&D Beyond to search every spell's description for the word "size".
Spells restricted by the caster's size
Disguise self (sort of):
You can seem 1 foot shorter or taller and can appear thin, fat, or in between. [...]
The changes wrought by this spell fail to hold up to physical inspection. For example, if you use this spell to add a hat to your outfit, objects pass through the hat, and anyone who touches it would feel nothing or would feel your head and hair. If you use this spell to appear thinner than you are, the hand of someone who reaches out to touch you would bump into you while it was seemingly still in midair.
So you can't appear substantially taller, as if you were a Medium adult. (Even dwarves, whom I'm guessing are the shortest Medium creatures, are 4-5 feet tall.)
Alter self's Change Appearance option:
You also can't appear as a creature of a different size than you, and your basic shape stays the same; if you're bipedal, you can't use this spell to become quadrupedal, for instance.
Spells (potentially) benefited by the caster's size
Tree stride (sort of - though it's not a sorcerer spell):
You gain the ability to enter a tree and move from inside it to inside another tree of the same kind within 500 feet. Both trees must be living and at least the same size as you.
In this case it's actually a possible benefit, in that you can move through shorter trees than Medium creatures can.
Shapechange (possibly - though it's a druid/wizard-only spell):
When you transform, you choose whether your equipment falls to the ground, merges into the new form, or is worn by it. Worn equipment functions as normal. The GM determines whether it is practical for the new form to wear a piece of equipment, based on the creature's shape and size. Your equipment doesn't change shape or size to match the new form, and any equipment that the new form can't wear must either fall to the ground or merge into your new form. Equipment that merges has no effect in that state.
That said, all equipment usable by Small creatures is usable by Medium creatures (as far as I know); if anything, shapechanging into a Medium creature would allow you to use Heavy weapons without disadvantage.
Special mention: a spell restricted by the target's size
Clone (a wizard-only spell):
This spell grows an inert duplicate of a living, Medium creature as a safeguard against death.
One of the the material components is also:
a vessel worth at least 2,000 gp that has a sealable lid and is large enough to hold a Medium creature, such as a huge urn, coffin, mud-filled cyst in the ground, or crystal container filled with salt water
The size restriction in the spell description itself (not the mention in the material components) is actually a recent change, made concurrently with the 2018 PHB errata - though it's a change not mentioned in that PDF. The same description that appears on D&D Beyond also appears in recent printings of the PHB, such as the one in the Core Rules Gift Set.
Previously, the spell simply said it could duplicate "a living creature", rather than "a living, Medium creature". The fact that it simply says "Medium" instead of "Medium or smaller" means that it's now impossible to use the spell to clone any Small creature. This seems like an oversight (presumably the intent was to prevent cloning Large or bigger monsters with it), in which case a future errata may fix it accordingly.