Vector2 origin = playerPosition;
Vector2 directionDown = Vector2.down;

RaycastHit2D[] hits = Physics2D.BoxCastAll(origin, boxSize, 0f, directionDown, distance, layer);

bool grounded = false;
bool touchingLeftWall = false;
bool touchingRightWall = false;

foreach (var hit in hits)
{
    Vector2 contactPoint = hit.point;

    float deltaX = contactPoint.x - playerPosition.x;
    float deltaY = contactPoint.y - playerPosition.y;

    if (deltaY < 0f)
    {
        grounded = true;
    }
    else if (deltaX > 0f)
    {
        touchingRightWall = true;
    }
    else if (deltaX < 0f)
    {
        touchingLeftWall = true;
    }
}

if (grounded && !touchingLeftWall && !touchingRightWall)
{
    //pafpafpaf
}