Well, not really, Winston1425. Annabelle can get to 5x5 at maturity (in about 10 years), even more if your growing season is long as it is in the South so, it will exceed the space that you are allocating to it. To try and keep it small, you can try to minimize the amount of nitrogen in the fertilizers (selecting those whose N in the NPK Ratio is small) but eventually, you will have to reduce the plant size (H x W) in the ol'e fashioned way... pruning it.
You can prune it at almost any time. The only time of the year when you should not prune Annabelle is when it is preparing to bloom in Spring. Nothing wrong doing it then, mind you. It's just that you would loose the blooms for that year. Pruning earlier in the winter may be better. It does not seem to care when you hard prune it during the winter time. Pruning often is not a good thing so try to prune so you do not have a yearly chore. The catch with pruning Annabelle often is that, under normal circumstances, the stems tend to plop down due to the large size of its blooms. It is thus recommended that you do not prune the stems often so they get stronger with the passing of time and therefore plop down less.
Instead of Annabelle, you may also want to consider Spring Meadow Nursery's Invincibelle Spirit, a pink-only Annabelle variant that is advertised a being less likely to drop after rain. It is also advertised in the size range that you desire. However, be aware that it is very new so the claims cannot be confirmed yet and it should also be expensive until production has ramped up enough, demand goes down or until the patent expires. This variant only blooms pink and does not turn other colors as the blooms mature.
For more information, see https://www.springmeadownursery.com/invincibelle.htm
PS - Whichever one you choose, be aware that hydrangeas will not stop growing when they reach maturity (that is merely a commercial guideline estimating the plant width and height at 10-years) so be prepared to prune once it starts exceeding its boundaries.