No , you got it all wrong , all spell slots are based on caster level
Like if you do 6 levels of sorc and 6 levels of bard you will still have lvl 6 slots. It’s just that as they don’t learn spells from scrolls , they won’t really have the lvl 6 spells.
But say you make a lvl 10 sorcerer and then 2 lvls paladin, this way you will have a lvl 6 slot which you can use for divine strike even though you won’t have a lvl 6 spell learned .
So it’s not really a wizard thing it’s how spell slots/ caster levels work , some classes get spells slots every level others every few levels but they all adds up to the total.
