Sugar maples are a very large tree when mature. They tend to grow with a rounded crown. Which means the branches do grow outward to stay in the sun. Making a 'ball' form eventually.

Bottom branches need to be addressed to keep the crown high where a certain clearance is necessary.

Topping a tree is the absolute worst thing you can do, ime.

Opening large wounds that are slow to heal and are entryways for pathogens and other things that can decimate a tree.

Here is one article: among thousands posted on the web about the reasons why you don't Top/Hat rack trees.

Forget about keeping these small. It would be better to replace them with something like Tatarian maple or Japanese maple. There are many trees that stay small naturally to choose from.