Cinnamon is used for many purposes (1). There is no single solvent or extraction procedure that is "best" for all of them. Which indication interests you? There will probably be a class of compounds that can use an optimized extraction.

(1) Article Effects of Cinnamomum zeylanicum (Ceylon cinnamon) on blood ...

cold extraction - maceration using appropriate solvent based on the group or class of phytochemicals you are targeting i.e solvent-phytochemical solubility in terms of polarity

According to required biological tests type of solvent controls phytochemical diversity of it is extract i am using 70% ethanol give high biological

results