Finding a value in a List

I need to find a value in a List. This is an example code that shows what I would want to do.

 private List<Space> spaces;
 private gridSize = 2.5;
 
 
 public struct Space{
    public Vector3 coor;
    public Vector3 pos;
    public int color;
    public bool isCircle;
    public Space(Vector3 c, Vector3 p, int cr, bool ic){
       coor = c;
       pos = p;
       color = cr;
       isCircle = ic;
    }
 }
 
 private static void CreateList(){
    spaces = new List<Space>();
    for(int x = 0; x < 10; x++){
       for(int x = 0; x < 10; x++){
          for(int x = 0; x < 10; x++){
             coorToPos(new Vector3(x, y, z))
          }
       }
    }
 }
 
 private Vector3 coorToPos(Vector3 cor){
    Vector3 newPos = new Vector3(cor.x * gridSize, cor.y * gridSize, cor.z * gridSize)
    return newPos
 }

So, in detail, what I really want to do is... I want to create a function so if I plug in the coordinate or the position of a point in the list, I would be able to get the color, and isCircle Boolean.

I know a foreach funtion will do this by: private Space FindTheSpace(Vector3 vectorCheck, isPos){ foreach(spacs in Space){ if(!isPos && spcs.coor == vectorCheck) return spcs; else if(isPos && spcs.pos == vectorCheck) return spcs; else return null; } }

However, I don't really want to use an foreach funtion because this is going to be in a foreach funtion. I really don't want it to be a double foreach function because I think it will lag too much....

So anyways, I hope you understood my question. If you did not understand something, please ask me. Thank you for your time and effort to trying to solve this problem I have

Thanks