What's wrong with the base class?
First of all, sorcerers spell options are way more limited outside of combat than any other full caster. Then there's the lack of known spells compared to other full casters. Though wotc recently tried to fix that issue. Here's a list of a few options that might bring the sorcerer up to speed.
A singular arcane spell list: Combine the wizard and sorcerer spell lists. This is a really simple solution that benefits both classes.
Spell Points: Use the spell points variant from the dungeon masters guide. At early levels it might feel the same. When you hit 3rd and 4th tier, this makes them way more flexible, with their casting.
Let the player choose: This might be controversial, but let the player choose the ability score they use for their spell casting. Sorcerous origins are not always the same. For example, one sorcerer might draw power from their bloodline and choose constitution, another might want to use their "force of personality" and choose charisma.
Sorcerer spell lists: WOTC mostly fixed the issue of sorcerers not getting enough spells. The only problem is they didn't retroactively update the rest. Here's what that might look like, if you're interested: