First of all, Lincoln did NOT own slaves. Not ever.
Secondly, people have argued for nearly 150 years about whether Lincoln did or did not free the slaves and whether the Emancipation Proclamation was toothless or actually had some juice behind it. It’s popular to say that Lincoln didn’t free the slaves and it is certainly arguable, but really, he kinda did. A war to preserve the Union eventually became a war to end slavery in the United States and that was a decision largely made and stuck to by Abraham Lincoln. People can and will argue and argue and argue about that point, but let’s look at it in a totally simplistic way: Slavery existed before Lincoln became President and began prosecuting the Civil War, but by the time of Lincoln’s assassination slavery basically ended with the Emancipation Proclamation, 13th Amendment, and surrender of General Lee to General Grant at Appomattox. Did Lincoln free the slaves by himself? No, but his idea of victory in the Civil War shifted considerably throughout his Administration from preservation to emancipation.
So, yeah, he kinda did.
The Emancipation Proclamation was largely symbolic. It freed the slaves in most of the areas under rebellion, not throughout the entire country, and almost all of the places covered under the order were controlled by the Confederacy at the time of its signing.
What it really did is signify that the Civil War was being fought for more than the suppression of a rebellion or the preservation of the Union. The Emancipation Proclamation made it clear that the abolition of slavery was a key objective in the war. With the Emancipation Proclamation, Abraham Lincoln basically married himself to emancipation as a condition of victory.
It doesn’t matter that the actual order was virtually toothless. The symbolism behind the Emancipation Proclamation helped lift the spirits of an oppressed people, helped establish a lofty cause for a nation exhausted by combat, and ensured that foreign countries would resist supporting or giving international recognition to the Southern Confederacy because of the North’s intention to abolish slavery.