I can give you my best armchair analysis but keep in mind that it's mostly just opinions based on my observations from a rural area and just enjoying data and trends.

My feeling is overall between the two major parties Missouri on a national scale is "comfortably red". The only thing keeping it from being solid red are the metro areas, like Kansas City, St. Louis, Jefferson City, and even Springfield to some degree. Years ago in 2012 I opined about Missouri not being seen as a bellwether when it didn't vote for Obama and after that it's trended more Republican with the senate seat flip of McCaskill's loss in 2018, the governorship flipping to Republican, and reliably voting Republican in every major election since. To compound this more is the local government which has carried a Republican supermajority for a long time now even well before that and shows no signs of changing any time soon.

On the other hand are amendments and issues. Most of the time these are not along party lines. Even though this is a conservative state in the Bible Belt, Amendment 3 with legalizing marijuana passed which feels opposite of what you'd expect. I've actually been surprised at the results of other measures in the past too, thinking "There's no way this will pass" and sure enough I'm proven wrong. My personal, albeit biased, thought on this is when you do not align an issue directly with the major political parties that people are more free to really think what is best for them and it turns more in to a purple situation. I actually feel if some Republican PAC would have put some effort in messaging by saying "If you vote Republican vote no on 3", then it would have failed because the people that vote on party lines would have went with it.

So TL;DR - On a national scale Missouri heavily favors Republican, on a local government scale it is solidly Republican, but on issues it's a mixed bag.