For example:
let line = this.add.line(null, null, 500, 500, 800, 400, 0xff0000 , 1);
//circle([x], [y], [radius], [fillColor], [fillAlpha])
let circle = this.add.circle(200, 200, 50, 50, 0xff0000, 1);
//circle.fillAlpha = 1;
//circle.fillColor = 0xff0000;
circle.isStroked = true;
circle.strokeColor = 0xff0000;
console.log(circle);
I get something like this