It isn't always easy to stand out in the job market and especially if you don't yet have working experience it is hard to get your first jobs.
However, even if you are experienced most of the code you worked on was proprietary locked behind the walls of your employer. You can't show that on your portfolio, not during your interview.
One way you might be able to improve your chances and overcome those limitations is by learning about the corporation you are interested in and learning about the software your corporation is creating.
Luckily these days there are many corporations that share some of their software under an Open Source license.
I've created a collection of corporations that have their Open Source stack in most of the cases along with their own GitHub Organization.
Then there are also a lot of companies that have a service or even a physical product that share some of all of their software under an Open Source license.
The ones that are well known for their Open Source projects such as Facebook and Twitter.
The other companies that are probably less well know for Open Source such as Booking.com and Disney.
And the companies that surprised me such as Mercedes-Benz and Samsung
And of course our host DEV that shared Forem
You can find the full list I compiled in this GitHub repository