A K1 visa is a request to the US government to allow you to bring your fiancée to the USA so you can get married. This starts with an engagement and an engagement ring and then wedding plans which are all included in your K1 visa package.
A visa package without significant wedding plans, photos of an engagement event etc will probably result in an RFE asking for this evidence.
Don’t forget you need 2 letters of intent to get married too signed and dated & properly filled out.