Switching to a business account will affect who your posts are shown to based on your business category. It may also affect which content is shown to you as well. It shouldn’t affect content which you’ve already posted, but will affect new content. It’s important that you choose a category which is most relevant to the content you’re posting. It will not throttle your post reach as most people claim, although in essence, by setting a category you are setting a niche industry for your posts to be classified as; this in itself may lower your post reach, but that really depends. Business insights are worth having for the small changes which occur as a result of the switch in my opinion.
I compiled two lists of every business & creator account category types a while back which may help you decide on the right category.