Though there's no standard size of a microcopy message, you're advised to keep it short but to the point. A short message is always easy to grab. But if it is still inappropriate, it is just going to confuse your visitors. The size of a microcopy message also depends on what you want to convey. Some messages can't be made shorter than a specific length. Your business objective & your product offer plays an important role in specifying the length of the same. The context of the message should also be clear. Or else, you must not decide on a microcopy message immediately. The context is the foundation of your message, so you have to pay ample attention to it. You can create more microcopy for different web pages on your site, depending on the foundation. Read more on https://bit.ly/3hB1pef