drawText accepts a maxWidth, when this width is exceeded it will wrap your text! https://pdf-lib.js.org/docs/api/interfaces/pdfpagedrawtextoptions

I figured out a solution after looking into the code for drawText. There is a utility function called breakTextIntoLines, that we'll need to run again to get the number of lines.

import { breakTextIntoLines } from 'pdf-lib';
//
// ... define font, doc, page ...
//

function wordWrapHeight(text, options) {
    const { font, size, lineHeight, wordBreaks, maxWidth } = options;
    const getTextWidth = (t) => font.widthOfTextAtSize(t, size);
    const lines = breakTextIntoLines(text, wordBreaks, maxWidth, getTextWidth);
    return lines.length * lineHeight;
}

const size = 20;
const lineHeight = size * 1.4;
const maxWidth = 200;
const wordBreaks = [' '];
const options = { size, lineHeight, font, maxWidth, wordBreaks };
const distanceDown = wordWrapHeight(text, options);
const y = page.getY();
const endY = y - distanceDown;
// TODO: Determine if the endY would take you off the page.
// If so, then split the lines up based on the amount of room left.
// Otherwise, you do this:
page.drawText(text, options);
page.moveDown(distanceDown);

Using courier font the inter character spacing should be perfectly even as it is monospaced, just add extra spacing to suit as you have done.

Your code should look spaced out like this, however I suspect your font definition courierBoldFont, may be wrong

Wrong definition of courier bold is not the same large spaces

I used sample https://jsfiddle.net/jw4b5rku/4/ for corrections to test courier behaviour so try your your code and versions of

<script src="https://unpkg.com/[email protected]"></script>
<script src="https://unpkg.com/[email protected]"></script>
to replace sample and see if its results differ when using courier