For me, "from the future" seems to bring the subject closer. Not necessarily that the future is not so distant, just that there is a way of bridging that distance. With "in the future", the future seems more like a separate, remote place. This fits the use of "from" for a toy that one can presumably play with now.
I don't know what the sentence " I like the robot toy that's shown as a soldier from the future." means to native English. When I follow the grammar's rules and the definition of from, that sentence doesn't make sense.
Here are the defintions and of from and in. You will know how to use from and in when you know their definitions.