What does "grand" mean? In which circumstances can I use it?
Answer from a Native speaker
In this context, the adjective "grand" means large or ambitious in scope or scale. Thus, we can understand "grand plan" as "big, ambitious plan." Grand is also used to describe things that are large and imposing in size, appearance, or style (similar in meaning to "magnificent" or "impressive." Ex: The villain had grand plans for world domination. Ex: The mansion was grand and imposing, with a spiraling staircase and marble floors.