The bard class feature Magical Secrets says:
By 10th level, you have plundered magical knowledge from a wide spectrum of disciplines. Choose two spells from any classes, including this one. A spell you choose must be of a level you can cast, as shown on the Bard table, or a cantrip.
The chosen spells count as bard spells for you and are included in the number in the Spells Known column of the Bard table.
You learn two additional spells from any classes at 14th level and again at 18th level."
You can choose any number of spells as long as they are available. Does this mean if I pick a high level bard, or just don't pick a magical secret spell at 10th level, can I use that say level 10 feature to pick a higher level spell from another class?
This is of course taking into account if you are allowed to wait to take the secrets by the DM.
Best Answer
I think the key problem is; how are you creating a high-level bard?
Every DM I've played with, and myself included, would say that you would create the character by going through the motions of leveling up to reach whatever the goal is.
So build a level 1 bard, fully fleshed out, then make them level 2 and do all the upgrades. Repeat every level until you reach the desired level.
If you don't level up normally, you can create impossible situations
For instance, at 10th level bard knows 14 spells (including two secrets). If you just created them at 10th level they could have all 14 spells be 5th level. Stupid, as you only have two 5th-level spell slots, but it makes a point.
During natural progression, you'd have to have a mix of 1st, 2nd, 3rd, 4th, and 5th. Here is a great question and answer about how many spells of each level are possible. It's asking about a sorcerer, but a bard progresses similarly.
So by saying your bard is suddenly level X, and now you can pick and choose based on essentially "always" being at that level you break some fundamental rules of the game.
Does that make it "wrong"? No, but your DM gets to make the choice of what is and is not allowed.
So as far as Magical Secrets go...
To my way of thinking, you should pick them as if you're at the level you gained the feature, not as if you are in your final form.