I want my Async function to finishs before my next function is invoke

I have an Asyn function that, with an URL of an image, resizes the image and send it to a /thumb folder.

The problem is that when invoking the next function "readFile()", the previous Async function hasn't finished yet, therefore there is not image in the /thumb folder.

I have tried different ways but I can't find a solution.

This is my image.ts file:

/* eslint-disable prettier/prettier */
import express from 'express';
import fsPromises from 'fs';
import path from 'path';
import resize from '../../utilities/resize';
const image = express.Router();

let myImagePath = path.join(__dirname, '/../../../assets/full/');
let myImageBuffer = path.join(__dirname, '/../../../assets/thumb/');

image.get('/', (req, res) => {
  myImagePath += `${req.query.filename}`;
  myImageBuffer += `${req.query.filename}`;

  const filename = req.query.filename as unknown as string;
  const width: number = res.locals.width;
  const height: number = res.locals.height;
  
  (async function resizer(width: number, height: number): Promise<boolean | undefined> {
    try {
      const result = resize(myImagePath, width, height, filename);
      return result;
    } catch (error) {
      console.error(error);
    }
  })(width, height);

  const myImage = ( function readFile(myPath: string) {
    try {
      const result = fsPromises.readFileSync(myPath);
      return result;
    } catch (error) {
      console.error(error);
      res
      .status(404)
      .send('Image not found, please provide the right name of the file.');
    }
  })(myImageBuffer);

  myImagePath = path.join(__dirname, '/../../../assets/full/');
  myImageBuffer = path.join(__dirname, '/../../../assets/thumb/');

  res.end(myImage);
});

export default image;

This is my resize.ts file:

import sharp from 'sharp';
import path from 'path';
import fs from 'fs';

const resize = function (
  filePath: string,
  width: number,
  height: number,
  filename: string
): boolean | undefined {
  const newPath = path.join(__dirname, `/../../assets/thumb/${filename}`);
  let result: boolean;
  if (fs.existsSync(filePath)) {
    result = true;
    try {
      sharp(filePath).resize(width, height).toFile(newPath);
      return true;
    } catch (error) {
      console.error(error);
    }
  } else {
    result = false;
    return result;
  }
};

export default resize;

Thank you