> {}{}{} ****
>
> Is the construction in bold suitable only for the folk tale style?
No. Only the sentence-ender has anything to do with stories. The rest of the part in bold is just very normal.
As discussed in this Q&A, is a common sentence-ending used by older characters in stories. It is role language that means the same thing as in Standard Japanese.
> [Noun] + +
means:
> "I want you to do [Noun]"
When the noun denotes a position or role as in the sentence in question, it means:
> "I want you to be/become a/the [Noun]"
as discussed here, expresses an exclamatory declaration in this context.
> "I really would like you/someone to be the young lord's playmate!"