I currently own a KIng Size platform bed and mattress. The mattress sits directly on the slats.
There is center support in 2 places. However the slats are 3.5 inches apart. The slats not flat but slightly concave.
I am thinking about getting a Latex mattress so I am trying to determine if my current bed is good enough or if I have to add some type of reinforcement.
Your slats are a little further apart than the suggestions in the foundation post here for an all latex mattress (which suggests gaps of 3" or less) but they would be fine for a latex hybrid that only had latex in the top layers and used polyfoam in the bottom layer.
If your slats are flexible then they may also change how your mattress feels and performs compared to a mattress that you test on a rigid foundation so that would be something to be aware of in your testing.
If you decided that any additional risk involved in having slightly wider gaps between the slats wasn’t worth it to you … you could always add a very firm layer of polyfoam or something like the bed rug here or one of the slat conversions here (which has no flex at all) or one of the Ikea slatted bed bases here (which has some flex which may change how the mattress feels and performs) or even a vinyl lattice like this which are economical and would provide good airflow under a mattress and reduce the likelihood of the latex sagging into the gaps over time.
I had read the foundation thread and learned that 3 inch max distance for the slats. Most likely I will go for all Latex mattress and the price of bed rug is so reasonable that I am totally fine in buying that to reduce the risk of mattress damage.