I often end up slipping into being somewhat bratty without even meaning to. I suspect that it's to do with the fact that although I do enjoy submission, actually reaching a headspace where I'm able to just let myself enjoy the experience can be tricky. A phrase that I've heard before that resonates with me is that in a scene, doms have control, and subs have the power. Well it's hard for me to exercise my power to relinquish control, because in regular life, I'm a fairly anxious person who doesn't like giving up control. To do so in a scene feels like transgressing my nature, in a way (and this is also why actually doing so in a scene can be so cathartic — I just need some extra coaxing to get to that point).

I'm also pretty bad with punishments, because I am very easy to upset. However, a useful word that I heard somewhere was "funishments" — basically just punishments that are actively enjoyable or wanted. So with my partner, we follow a protocol of "no actual punishments, only funishments" (to the extent that outside of the initial discussions we did on this topic, we just use the word punishment and understand that we're talking about funishments, because it's less immersion breaking)

Examples of funishments include:

• "Making" me go down on my partner for a while (something I'd do gladly anyway — if anything, getting the amount of dedicated focus on me that my partner typically gives me is difficult for me sometimes. )
• Restraining my hands (especially effective if it's framed like "if you can't be trusted to do what you're told...")
• If you're stronger than a bratty partner and don't usually just physical force against them and are mainly about psychological domination, then pinning them down can be a teasing reminder of "I could do this at any time, you know"
• Physical pain is also a thing I really like, in moderation. Even during fairly vanilla sex, the occasional sharp bite to my neck, nails raking across my skin, or a slap on the ass can feel really good. I have a pretty low pain threshold though, so these are things we've had to practice to calibrate our mutual understanding of how much pain is enjoyable both for me and my partner (my current partner struggles with actually dishing out pain, but practicing this and dishing it out as a funishment occasionally has helped them to feel more comfortable about it too — because like I said above, funishments are things that I would actively enjoy, just wrapped up in the rhetoric of punishment.
• Edging play can also be a good way to make a bratty sub regret their choices (in a fun way). This can be especially effective if the edging itself happens later in the scene than the brattiness did.

Sometimes with a bratty sub, it's about giving them what they are asking for. Like one time that's a highlight to me, my partner had given me a slaps on the face, on my right cheek. I pouted and said that now my left cheek was feeling neglected, and that they should give my left cheek a slap, for symmetry. The initial slap was near the upper range of what I find tolerable, so I felt a bit silly to let my bratty nature win and literally ask for more. Before I received the slap to my left cheek, I apparently flinched in a humorous way. The fact that my bravado had been challenged successfully was something that helped me get into a more submissive head space.

To put it another way, sometimes a bratty sub is playing stupid games and actively hoping to win stupid prizes. For me, the fact that not playing along leads to different treatment than I had straightforwardly submitted makes the submission feel more weighty. The key to bratty subs is understanding that they do actually want to submit — they just need a little extra help to get there

But also, it's fine if that isn't a dynamic you enjoy much, even after figuring out how to successfully pull it off. I mean, I wouldn't ever be compatible with a dom who was into intense pain play and degradation, even if I did train my pain tolerance. Domination and submission are so multifaceted that a big part of exploring in this space is just figuring out what aspects of that is we most enjoy. Different strokes for different folks.