score:5
Yes, it is possible. The Schengen Borders Code says nothing of return tickets. The "entry conditions for third-country nationals" are specified in Article 6, and the relevant part is item 1(c):
they justify the purpose and conditions of the intended stay, and they have sufficient means of subsistence, both for the duration of the intended stay and for the return to their country of origin or transit to a third country into which they are certain to be admitted, or are in a position to acquire such means lawfully;
As you can see, this is vague enough that you should be fine as long as you have a credible plan to return to Brazil or another country where you are authorized to reside. There's nothing to prevent you from doing so by first traveling to another country by land.
In addition to having a credible plan, you might be asked to show that you have enough money to buy your bus or train ticket out, if you haven't already bought it. Or if you're planning to drive out with a friend, they might want to call your friend to confirm your plans. The chance of this happening is pretty minimal, however, in my experience.
Upvote:2
Entry to the Schengen zone does not require proof of onwards travel as a hard requirement but it would not be unusual for a border officer to ask for some proof that you intend to leave after your planned stay.