My wife is applying to another retail job at the manager position what should her cover letter be like?

Currently, she’s a co-manager at a very large trendy retail store. She wants to apply to a trendy store that is less in volume. She’s applying as a manager. Currently she’s one step below the store manager position. She believes she can work her way as an assistant to store manager at this smaller chain.

What advice or recommendations would you have for her on her cover letter?

Thanks so much fellow jellies!