The phrase "to take on the world" means to confront or face a difficult challenge, often used in the context of someone or something that is determined and courageous in the face of adversity. Full definition
When it comes to taking on the world of online dating, it always helps to have a best friend on your side. (eharmony.co.uk)
The only problem is that shortly after, fear returns, followed by an inner critic attack because you're not a fearless warrior taking on the world with ease like other people. (mindbodygreen.com)
Two friends can now team up online and take on the world in tag battles. (tomsguide.com)