[DobbysGamertag]

for checking if they're in a CP:

pawn Код:

CMD:something(playerid,params[])
{
    if(IsPlayerInCheckpoint(playerid)) //they are
    {
        //code
    }
    else //they arent
    {
        //code
    }
    return 1;
}

The size of the checkpoint:

pawn Код:

SetPlayerCheckpoint(playerid, x, y, z, size)

The last parameter.

I reccomend using a streamer though. Since

Quote:

Checkpoints are asynchronous, meaning only one can be shown at a time. To 'stream' checkpoints (only show them when players are close enough), use a checkpoint streamer.

Incognitos does this iirc