Essentially, the Emancipation Proclamation hardly freed any slaves. What freed the slaves was the 13th amendment. Instead, the Emancipation Proclamation was more of a tactical tool. The biggest reason for this being to prevent the Confederate States from getting oversea allies. You see, the Confederacy greatly desired the help of Great Britain more than anyone other. Abraham Lincoln realized how game-changing help from them could be, and basically, the Emancipation Proclamation sealed off any possibility of Great Britain joining the Civil War to aid the Confederacy. Unlike most people tend to say, the Civil War was NOT about slavery, instead it was mainly about state’s rights. However, establishing the Emancipation Proclamation MADE the war about slavery. As slavery was outlawed in Britain at the time, it would reflect very poorly on the government if they were to assist people who were pro-slavery.

To answer your question, Abraham Lincoln did not extend any power over them, which he already knew would be the case. As previously mentioned, the Emancipation Proclamation was tactical decision made by Abraham Lincoln after the close victory of the battle of Antietam (Enacting something like the Emancipation Proclamation after a defeat would have looked desperate more than anything, after all) to deny the idea of Great Britain joining the Confederate war effort.