Canva is a fantastic website (www.canva.com) for creating designs. While it is targeted at the general public, it contains lots of great assets that designers can also use. When creating a design, the Elements section contains lots of vector based (ie not pixel based) artwork. When downloading a file from Canva, ensure that one of the PDF options is used which will preserve the vector content. Opening the PDF in Illustrator allows for the vector artwork to be easily manipulated.