If you're interested in this topic, the thing to Google for is "constitutional theory".
Constitutions do not just limit power. They prescribe how a society organizes itself, including how to exert power (not just how to limit it). A major goal for democratic constitutions is enabling a society to make collective decisions.
E.g. the US congress is famously struggling to make decisions. An interesting question then is how the US constitution prescribes decisions must be made, and whether that framework of decision making is successful along certain criteria (e.g. representing voter will, protecting fundamental rights).
If you're interested in comparing to other constitutions, a good way might be researching countries that "score well", e.g. that have stable governments, non-violent transitions of power, successful decision making, score well on the human development index, etc. - or countries where things are going particularly poor. I find that the positive example is often more interesting, because the poor outcomes often have major negative factors that might not apply in other countries and might not relate to their respective constitution.
Countries that come to mind would be the likes of Sweden, Japan, Botswana, New Zealand, but your mileage may vary depending on what you consider to be positive outcomes for a society.