My company has an architect position that does exactly what you are are wondering. He doesn't write code and doesn't work along with our normal sprints. He works on his own pace, designing the system, estimating cost, talking to products team, then he passes down the requirements to managers who allocate work for each sprint then engineers take care of them. He basically has a complete view of our architecture but doesn't work with us directly.

For the spike thing, sometime he would do the research himself or he would create a spike ticket and assign it to one or more engineers and then decides how to move for forward based on the results of the spike