D&D 5E 5e, No expansion: Sorc5/Wlock2. Help with some numbers.

[RulesJD]

Except Warlocks get you Warlock Cantrips, so your number of cantrips known does change. And Warlock spell slots gives you extra low level spell slots at the cost of eventual high level slots, so it also effects your spell slots.

So yeah. Multiclassing into Warlock makes a huge difference.

Sorry, I should have phrased that differently. It makes zero difference to your SORCERER spells/cantrips known. Unlike multiclassing to any other class as a Sorc (like say a paladin), you don't need to worry about multiclassing spell slot rules. If you're Warlock 3/Sorc 6, for the purposes of all things not Warlock, you are a Sorc 6 with as many spells/slots/cantrips as a Sorc 6 (with the exception that you can cross-class cast and burn the warlock spell slots to fuel metamagic aka the greatest thing ever).