New emojis are introduced into Unicode every year. These are decided by the Unicode Consortium, which selects new images based on relevance to a global audience.
Emojis are introduced based on their relevance to global populations. They are therefore entirely context-dependent, and intended to reflect the world we live in, rather than to influence or lead it. For example, in 2015, the Unicode Consortium shifted away from the homogenous 'white-washed' yellow skin tone. The group introduced an additional five 'skin' shades to diversify the range, and be more racially inclusive to users. This was a response to growing movements for action against racism (and other forms of discrimination) within tech.
Emojis may reflect trends in attitudes, but in popularising these they serve a much broader purpose. They popularise and spread these changing cultural attitudes by virtue of being so widely used.
[P1] New emojis are introduced annually [P2] Emoji selection is based on how relevant they are to a global audience [P3] Relevance is based on critical trends and attitudes that have shifted since the previous selection
Rejecting the premises
[Rejecting P2] Emoji selection is based on far more than world events. For example, it is also based on data around use of existing emojis and how people are using them.