Final answer:
Stranger Things created an '80s theme through marketing strategies with nostalgic brands, social media engagement with '80s references, and a soundtrack featuring classic hits from the decade.
Step-by-step explanation:
The show Stranger Things (ST) established a theme of the 1980s outside of the actual series through various means. One prominent method was the marketing strategy, which included partnerships with brands that were popular during the '80s, as well as the release of nostalgic merchandise. The show's creators also engaged with fans through social media, sharing throwback posts and '80s pop culture references. Additionally, the soundtrack featured classic '80s hits, which were made available on streaming platforms and for purchase, further enhancing the retro experience for the audience.