I tried creating a mirror with a fully reflective material but it only reflects with my SSR and that’s terrible. I also tried using a scene capture 2D but that only makes my game super laggy and the player’s coordinates in the reflection is way off. Anyway to create a realistic mirror?
check out planar reflections 
Yeah but the problem with that is it only reflects what ever your camera sees.
Eh, no. Thats what Screen Space Reflection does.
Planar Reflections let the environment render twice.
planar reflections uses its own camera actor to create reflections independent of screen space
How can you turn off SSR? Because it still seems to screw around with the edges of the mirror. As well as it’s kinda not the resolution it should be. I set it to 1024 but it’s not good.
the settings for SSR are in the post process settings down the bottom
Turning off SSR will make the rest of your scene suffer as a result, though.