SOURCE

let h=180;
let points=10

function setup() {
 createCanvas(500,500);
 background(255);
}

function draw() {

    if(keyIsPressed){

        if((key=='q')||(key=='Q')){
           h+=5;
        }
        else if((key=='w')||(key=='W')){
           h-=5;
        }
    }
    if(keyIsPressed){

        if((key=='a')||(key=='A')){
           points+=1;
        }
        else if((key=='s')||(key=='S')){
           points-=1;
        }
    }

    stroke(h,100,100)
    strokeWeight(points)
    if(mouseIsPressed==true){
    line(mouseX,mouseY,pmouseX,pmouseY);
    }
}

<script src='https://cdn.jsdelivr.net/npm/p5@1.1.9/lib/p5.min.js'></script>