Question

A line passes through (2,1), (0,-2), (-2,-3), what is the y intercept?

Answer 1

It will be `y=-2`
You can see this from your second set of coordinates where for `x=0` you get `y=-2`:
Graphically:

Answer 2

Obviously, given the second data point `(0,-2)`
`(-2)` is a y-intercept
but the given data points (2,1), (0,-2), (-2,-3) are not points on a straight line,

The underlying equation could be a parabola (with a horizon axis of symmetry) or some more complex relationship.
Other y-intercepts are possible.