If you want to make a cake in rice cooker without cake paper you have to grease it with salad oil, and you need to preheat it before you grease it, and you need to grease it evenly.

I don't know what kind of cake you need to make, such as chiffon, sponge or hot chiffon cake, among these three, I have made chiffon with rice cooker, and it has been successful, but, leaving aside all the aspects of doing, the most important thing is the rice cooker, please remember, you can only use the old-fashioned rice cooker to make the cake, that is, once you heat up the pot lid will follow the heat of the kind of, it looks a little bit like the top and bottom of the oven tube heating principle. This looks a bit like an oven with top and bottom tube heating. Other newer rice cookers won't do it at all, let alone electric pressure cookers, because I've tried them all and they all ended in failure.

And you said you want to use cake paper, so no need to come back and grease it, because greasing is to prevent sticking, and with cake paper it won't.

I also think it's well said and messy, I hope it helps, it's a tough road to make a cake, but if you learn it, then it's really enjoyable, and I hope you get pleasure from it.