Well, it's actually a very complicated issue. If you want to know whether the use of agogic accents is a part of authentic period practice, then it depends on what composer, what type of music, etc. They were used throughout the 18th and 19th centuries, scholars think, but since there is no standard notation for them it's very hard to get a handle (or Handel) on it. Certainly they would be used very differently in Bach and Chopin.
On the keyboard, I can imagine using them in the C minor prelude from WTC I, for example, but probably not in every bar. I would say in general they would be used to relieve the monotony of what would otherwise be an endless series of 16th notes (as in the cello suite).
Searching online, I found a few references to them in Roger Norrington's book:
https://tinyurl.com/67fjopOr you could check Grove's dictionary...