[DiogenesLamp]

It emancipated was all slaves in states still engaged in rebellion against the Union. Although implementation was strictly beyond Lincoln’s powers, the declaration turned the war into a crusade against slavery.

The London Spectator mentioned at the time that the message given by Lincoln's actions was not that one man could not own another. He could only own another man if he was loyal to the Union.

[BroJoeK]

"He could only own another man if he was loyal to the Union."

British wags & wit notwithstanding, that was the US law -- absent a Constitutional amendment Lincoln had no authority to abolish slavery in Union states.
But Congress could & did abolish slavery in Washington DC, and in western territories.
It could also declare slaves in Confederate states as "Contraband of war", which it did.
Union states could also abolish slavery on their own, which all but two did.

That left only Delaware and Kentucky with slavery still lawful, but they had very few slaves to begin with and by 1865 most of them had been freed by their "masters" or had run off.

The 13th Amendment just made Constitutional & permanent what had already happened, long before.