Cap rates are only snapshots of the future. Remember that the cap rate is based on current income and expenses. However, it does not account for new renovations, changes in management, marketing differences, etc. As the investment term progresses, these factors can cause a cap rate to rise or fall.
Nevertheless, appreciation is a theoretical possibility and could not occur depending on the market. You can be more certain about the rent you pay and your net operating income than the market. Real estate income isn't the only way to make money.
Remember that assets with steady monthly cash flows don't appreciate very much over time. A high area capitalization rate can produce a large monthly cash flow, but it doesn't appreciate very much over time.
Cap rate does not take appreciation into account. Multifamily properties can appreciate (and often do). This is what determines what makes a good multifamily cap rate. For example, the cap rate in San Francisco is so low. Because the land itself is so valuable, there has been a lot of appreciation potential over time, even though the ROI is low.
Let's sum it up: What is a good multifamily cap rate? It is not possible to find a single "good cap rate real property" that can answer this question. There are many factors that influence whether or not a caprate is reasonable, such as your risk appetite and where you live.
You probably know that cap rates are only one part of a deal. While they are fundamentally and vitally important, they are just one aspect of a deal.
You should also consider your investment goals and criteria. Knowing your investment criteria will help you identify the deals you're looking for and how you can use the capitalization rate in order to find the best deal for you and your investors.