Comment by Sawamara

You are right that it takes luck or very careful strategy to be able to learn multiple fields within programming inside one single company. In my current place, I consider myself very lucky that I got the opportunity to do multiple languages (starting off as TS, to move into C# and backend), and also had the chance to do a (p)React-based ui redesign as well, so that ticks three boxes without having to move around.

But lets not forget that many companies usually do change up web stacks as well, so there might be opportunities every now and then too.