How to move to Lead and staff Roles

I am a senior software engineer and worked mostly in the backend and I think that I can do a decent job designing tables, HLD, LLD. However I have mostly worked at large companies where your role is limited and when asked questions like “tell me a scenario where you solved a critical bug in a high traffic situation”, I don’t have anything immediate.

How can I get better at such things when there isn’t a high traffic scenario in my company. What are the other things that a lead/staff engineer should know? Is there any preparation material using which I can prepare myself for lead roles at FAANG companies?