Let me start by defining what is “complexity” in front end development in my experience.
In the case of a front-end professional, complexity doesn’t come from having to solve huge complex problems that requires (too much) logic, algorithms, and intricate time/space performances.
The real complexity comes from the needs of familiarity with tools/technique you may or may not know.
Or in other words: you have to learn fast.
Let me elaborate a bit about it.
If I compare the “professional” myself now, with the “learning” myself a (little) while ago I guess the main difference is that now I cannot spend too much time prototyping, trying and researching.
If I receive a request now to implement something, I cannot trial/error my way to the solution like I did while learning.
I have to already know how to proceed, do a little research while working, and be confident that what I’m doing will be right.
The same applies when learning new tools.
It’s obviously that you cannot know everything, but it’s required that you learn the least minimum to start working and be productive in a shorter time that what you may have been used to while learning.
This does not means that the job is “easy” and you are just a typing code machine.
Often you’ll be asked to implement something that will require you to actually sit back and think about it and that legitimately you have no idea how to do it.
The learning myself would simply dismiss it with a “I can’t do that, I’ll do it this other way that I know instead and it will work regardless”.
On the job this attitude is not permitted, you can’t just change the requirements because is more convenient for you.
Here the best advice I can give you is the same my senior gave me a while back when I was confronted with the same problem:
In CS there’s no “it can’t be done”. There are just things you know or don’t know how to make.
And that’s why in my opinion the best asset you can have to “be hireable” for a junior/starting position is to show that you’ve already developed some projects for yourself.
Because, as said, on the job confidence is the key; and practice is what helps you build it.
If you have any more questions I’ll be happy to reply