Hi,
Our child is past 7 and still is anxious, though perhaps not as serious. But we have ongoing managed it in different ways.
Role playing. We did try doing the what if game and taking it into a comedy routine. So we take the anxiety and imagine something even worse that could happen. But we've been doing this for a long time ever since 3-ish we've been doing something to manage fear of this or that. We also typically talk out our own fears so child can hear how we hope to handle it, etc.
We take a lot of time planning, verbalizing the plan, offering options to plans so that, if this doesn't work, we might try this...
There is still separation anxiety.
I'm thinking it is because our children can imagine greatly and feel things deeply.
Also we spend time helping child remember conquering past fears/anxiety. Remember that time you felt this/that, and then what happened once you got there? You had fun? No way!
I'm wondering if it is mostly helping them understand their feelings won't overwhelm them, and to show them how to manage their own brain activity.