Hello,
Can any body suggest if Mikrotik supports SDN. If yes, then is there any study material available for the same.
Thanks

Nope, no such product that I'm aware of.
The thing is, in order to have a solid SD-WAN solution you need to understand what applications you are transporting.
Sure creating "some overlay" network with Mikrotik is possible off course today, and SD-WAN also does that in a way, but to understand the applications and create transport policies around that is some whole other game.

I've been doing some Riverbed work in the past, now we are doing SD-WAN on Nokia/Nuage , Cisco , Palo Alto, Fortinet etc.

Thanks a lot for the response. Are there any open source SDWAN solutions, that can be used to get some hands on experience.

https://flexiwan.com/ ?

Not fully "free" offcourse in a real-world scenario with dozens of remote sites, but free up to 3 "edge" instances.