Is it possible for am actual emotion to be a trigger at times?
Well, there's the concept of primary and secondary emotion.
Primary emotions are the ones we identify as the feeling we are having. Secondary emotions are the feelings we have surrounding that initial emotion. AKA, "feelings about our feelings".
When I'm angry, I often immediately feel afraid. The combination of those two leads to feeling overwhelmed, and then secondarily ashamed. Generally, I'll end up crying. That's an example of primary and secondary emotions chaining together to create responses that can seem oddly disconnected from the initial feeling (the primary emotion) that sparked the whole thing.
People experience secondary emotions in all sorts of ways, and I often suspect that PTSD/CPTSD folk confuse secondary emotions for being triggers. I'm not saying you do this, BTW - it's just something I've wondered about. It's easy to miss the secondary emotion unless one stops and notices it.
When someone experiences joy and then weeps, it can be the primary emotion joy, and the secondary emotion, relief. The tears might be more rooted in the relief than the joy itself.
And for anyone who struggles with emotional regulation as a result of their diagnosis - the intensity of the primary emotional response, coupled with the intensity of the secondary emotion that is generated, can result in the state we call 'flooding', which could then lead to freezing.
The advantage in understanding and identifying secondary emotions is that one can then work with them. Simply slowing down enough to clock the feelings we have about our own feelings can truly result in a better understanding of how to manage them, how to shift them, how to connect the dots between those feelings and the distorted thoughts or (negative) core beliefs that inspire them.