Yep. Science Daily says it’s a good idea to talk to children using grown-up language:
Academic language is characterised by difficult, abstract words and complex sentence structures. The language often contains a lot of clauses and conjunctions and due to the methods of argument and analysis it has a scientific appearance.
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Henrichs demonstrated that children are already confronted with academic language in the nursery school.
…An essential aspect is how parents approach their children during conversations. If children are given the opportunity to make meaningful contributions to conversations, they often use characteristics of academic language proficiency naturally. In addition to this, the knowledge of academic language depends on the extent to which parents read to their children, tell them stories and hold conversations about interesting subjects.