Code for gridColour[x,y] == gridColour[x+1,y] || colour at [x-1,y] || colour at [x,y+1] ||colour at [x, y-1] to detect if 4 of the same colours are connected?

Please help I've been trying to work this out for a few days

How do you write code like this screen shot to detect that all of these tetrominos (within its parent game object) have 4 of the same colour tetromino connected? colour tag at [x,y] == colour tag at [x+1, y] || colour tag at [x-1,y] || colour tag at [x,y+1] ||colour tag at [x, y-1] ?

My game is similar to this screen shot, but it has 2 random colour tetrominos within a parent game object, each tetromino is tagged "red" or "blue".. I want to detect once 4 or more of those same colour tetrominos tags are connected those tetrominos destroy and the grid is updated..