Truth is what is true.
For something to be true, it must make logical sense.
"Logical" doesn't mean it has to exist in the world as we know it.
"In a world where the sky is green and grass is red, that outfit would look good." - This is probably true, depending on the outfit.
Truth is mostly conditional, since all things seem to be relative. "If 2+2 = 5, then 2x2 = 5," would be, with some limits, a true statement.
It's all context. Without the background to hold something in place, such as the concept of numbers and the concepts of addition and multiplication, it's hard to have any truth.
Logic functions only in context.
But how does one separate the context from the logical proposition itself? They are endless.