In the previous version of Scrum guide, there were 3 questions to discuss in daily call. But it was removed as the developers can decide whatever structure they want.
Sameway I see for retrospective, it is given in guide as below,
The Scrum Team discusses what went well during the Sprint, what problems it encountered, and how those problems were (or were not) solved.
which also looks like a format or alteast used as a format in lot of tools for retrospective. Not a problem just my viewpoint.