Lore bard magic secrets help

[Yamatohekatsue]

So I'm building a character for a high level game and starting at level 18
I'm making a sorcerer 12 bard 6
My bard is a lore bard and I will get magic secrets. Because of my multiclassing I have a few questions about magic secrets.
It says
At 6th level, you learn two spells of your choice from any class. A spell you choose must be of a level you can cast, or a cantrip. The chosen spells count as bard spells for you but don’t count against the number of bard spells you know.

Source: Player's Handbook, p. 55

Because I'm lvl 18 I have 8th level spell slots but my highest level spells from sorcerer are only level 6 bard is level 3

Because I have 8th level spells slots can i pick something 8th level?
Because I am a sorcerer can I pick something 6th level?
Or can I only pick 3rd level cause my bard can only learn spells of that level?

[Chugger]

I would say no, you can steal a cantrip, level one, two or three spells.

You steal higher level stuff at higher bard levels.

Why do you want six levels of bard?

[elyktsorb]

"At 6th level, you learn two spells of your choice from any class. A spell you choose must be of a level you can cast, as shown on the Bard table"

Which means you can only steal spells you would be able to cast as shown by your bard level, not your total level.

[Yamatohekatsue]

Conjure Fey, and flesh to stone both warlock spells

[Yamatohekatsue]

"At 6th level, you learn two spells of your choice from any class. A spell you choose must be of a level you can cast, as shown on the Bard table"

Which means you can only steal spells you would be able to cast as shown by your bard level, not your total level.

True but because I'm a multiclass dont I use the multiclass table for spells?

[Yamatohekatsue]

Basically I'm a wild magic sorcerer halfling I want to use my metamagic heighten spell to give disadvantage on the save for flesh to stone
Most of my spells revolve around targets having to save, and heighten helps with then having disadvantage, I'm trying to build a control build and figured petrifying targets would be a great form of control.

[elyktsorb]

True but because I'm a multiclass dont I use the multiclass table for spells?

No, that table is just to show you how many spell slots you have overall. Furthermore it wouldn't matter because even if you did use that table the ability still states it has to use the Bard spell table, which would make the multiclass table irrelevant anyway.

[Yamatohekatsue]

Dam well guess I'll be a 15 sor 3 bard cause I want Cutting words

[supercereal]

Dam well guess I'll be a 15 sor 3 bard cause I want Cutting words

Why not 15 bard and 3 sorcer? You get flesh to stome from magical secret al level 14, cutting words and metamagic. You only have 3 sorcery points but you can burn low level spell slots to make more

[Yamatohekatsue]

I would have to spend more time converting spell slots in battle. And I won't get my wild magic abilities like bend luck extra metamagic bend luck and controlled chaos

[diplomancer]

"Spells Known and Prepared. You determine what spells you know and can prepare for each class individually, as if you were a single-classed member of that class."

PHB, page 164, Multiclassing chapter.

So the magical secrets hack doesn't work.

Cutting Words (or metamagic) is fun and all, but is it worth it giving up on 9th level spells for it, including Wish? I wouldn't recommend it.

Also, there are better forms of control than flesh to stone, and remember that the Heightened metamagic only affects the 1st saving throw (and at that level many creatures will simply pass with Legendary Resistance). For a combat, using a 6th level spell and your concentration to keep one creature restrained is pretty bad.* Compare it, say, with Hypnotic Pattern; 3rd level spell, several creatures, incapacitated, and, if you have an Instrument of the Bards, disadvantage on the saves.

For creatures with Legendary Resistance, what you want are controls that don't allow Saving Throws.

For instance, the Class Versatility UA added Maze to the Bard's spell list. If your DM allows it, that is a far better form of control than flesh to stone (no Saving throw, very hard to escape). Even if he doesn't, it's a great pick for an 18th level Magical Secret (alongside Wish).

* For what it's worth, Treantmonk, on his analysis of 6th level Wizard Spells, give Flesh to Stone a Red rating. I'm inclined to agree, no way I'm using a Magical Secret for that.