With me, my little side is between 9-12 years old. I'm not into pacis or bottles, plushies or sippy cups. I can get little by playing with toys sometimes, or colouring in or watching cartoons, but admittedly not often.
For me, being a little boy is all about pee holding, desperation and wetting.
I like to dress a bit childishly, like short shorts, colourful t-shirts and white ankle socks, or I have some grey shorts and a white shirt that looks like a school uniform when combined with the socks, and I like to be getting desperate to do a wee, but I'm too busy playing or distracted by what I'm doing to go to the toilet.
I'll hold myself, cross my legs, march on the spot, stuff like that, until "little me" has an accident and wets his pants.
If I have diapers, I'll wear one under my footed onesie or pyjamas, sometimes already wet, like it's how I've woken up but I haven't changed yet, so it feels naughty to be a "big boy" in a wet diaper, and I'll wet it again, probably making it leak.
So for me, 95% of the time it's revolved around potty mishaps or desperation