Like most things in the digital world, its usually easier to use tools designed for the job. Many of these presentations are prepared using third-party products. One that has become really popular with marketing companies is PowToons. This is an online services that allows you to make animated presentations based on pre-made slide templates. When it's completed, you can download it as an MP4 file (premium users only).
Another way to create these types of presentations is to use a presentation editor that includes animation options. You could even use an HTML animation application. For most people powerpoint or Keynote has the tools to do this. You start by adding the text as a normal text block in any suitable handwriting font. This has a typewriter animation effect applied so that each letter appears on the screen one at a time (adjust the speed of the effect accordingly). Next, add a path that follows the ups and downs of the font strokes. Add a gif or svg graphic, if supported, of a pen or a hand holding a pen and size it accordingly. Have the graphic follow the path with your application's "animate on a path" function. Have the animated graphic start simultaneously with the typewriter animation effect and adjust it's timing to match that of the type-in text effect. When the whole presentation is completed, output to an mp4 video.
To make the effect look convincing, it's important to prepare your pen and hand graphic carefully. It should be on a background the same colour as your presentation page and it should be close-cropped to the point of the pen or pencil. This will ensure the remaining graphic and it's background covers the underlying type-in effect of the letters, causing the letters to reveal at the point of the pen or pencil as it travels along the path. The attached is an example graphic. The grey area would be set to the colour of the presentation background. Of course, it's also important to ensure that the point of the pen or pencil is the part of the graphic that aligns to the animation path.
I've attached a simple example MP4. This took a couple of minutes to make.
If you want to try out the PowToons option, here is the URL to some of their tutorials. https://www.powtoon.com/tutorials/