Yes of course. (I was hoping Edward might chip in here as I’m not fully familiar with the restrictions on Effects on FLX-S!).
You could approach this several ways. I think with FLX-S you mostly have to use the preprogrammed effects palettes.
It’s probably easier to deal with the intensity and movement parts separately. So I’d select your fixtures and have a play with the Effects marked ‘I’ which are intensity effects and see if there is something there that suits. You should be able to adjust the speed and ‘size’. I think there is a 1/8 intensity effect which might be a start.
On the movement side it depends what you want to do. Again, look at the Effects marked ‘P’ which are position effects. There are circles, figure-of-8, fly-in etc. maybe one of them suits with adjustment to speed and size.
If the existing Effects palettes get you something you like, you can layer each type onto your fixtures. When you’re happy you can then RECORD this new composite effect to a new effect palette. Ensure the palette when recorded is marked with I and P.
If you want to do something quite different on intensity and movement than what’s available from the Effects palette then you will need to go down the route of programming a sequence. You could do this all on one playback, but if you wanted independent control of intensity and movement you might want to put each on a separate playback then overlay the two, maybe triggered from another playback.
Maybe time to have a read of relevant parts of the manual and have a search on this Forum for similar questions as there are details you’ll need to understand (like tracking and only recording certain attributes).
Good luck!