Magical secrets come at 10th level bard, If I´m not wrong. You do get different spells because you multiclass with a sorcerer, sure, but you have to pick spells from the mage pool, not cleric, druid or warlock spells that are very useful for a bard that is not a pure caster, like sword and valor bards, but it´s a very strong build to multiclass with a sorcerer, yes.
