As far as I know sirens in France (back in the ol' days) seldom had timers, it was just a plain power relay tied to a push-button that you'd manually had to press (right now I kinda regret having passed up one of these on Leboncoin given how extremely rare these are...) to activate the siren manually, sometimes you'd have a break-glass control point outside (although this is really rare these days... There's two towns in my area that still have these outdoor siren control points but they're all but disconnected), in short, you were the timer so to speak
There was also a version that relied on land-line loops and would be activated from a central office, but unfortunately I cannot find any information about this system.. :/
Later timers (known as S.A. Demay or Moteurs Fox timers) are kind of like a AR timer but with a few differences, you have three buttons: signal d'essai ("Test signal"), Alerte aux Populations ("Alert"), Fin d'alerte ("All Clear") and no button to stop the cycle, and most importantly, under the hood these modern timers rely on a PLC to do the timing stuff instead of a set of cams and a motor.
If I remember correctly the UK also had some interesting siren timers they worked in the same way an AR timer would, but were much more compact, I've had made a few notes about these before but I cannot locate them at the moment, I know these had one buttons to trigger the warning signal and another for the all clear, and that's it, they were very simple, and there was also multiple versions over the years too...