Putting it all together

Cool! Now you have a model to handle your slides. All you need to do now is to bring it into your sketch

let myModel; //make a variable to store your model in
let sketch1 = {};
let sketch2 = {};
let sketch3 = {};

function setup() {
createCanvas(windowWidth, windowHeight)
defineSketches() //

let titleOptions = { 
    "header": "HELLO, WORLD!",
    "subHeader": "subtitle",
}
let titleSlide = new StaticSlide(titleOptions)

let endOptions = {
    "header": "Thanks! (◡‿◡✿)"
}
let endSlide = new StaticSlide(endOptions)
myModel = new Model([titleSlide,
                    sketch1,
                    sketch2,
                    sketch3,
                    endSlide])
for (slide of myModel.slides) {
    slide.setup()
}
}

Drawing

function draw() {
myModel.draw()
}

Input

function keyPressed(){
myModel.getInput(keyCode)
}