Quanta doesn't have a design for this as it is not not designed to support container blocks.
In most cases you would click on a block inside the container and add before or after
But what about when the container is empty?
Ways to support it could be
quanta toolbar menu "add inside"
where text is allowed, have a new block always appear when you delete the last one and you can then change its type. or if only one type allowed (like column in columns block)
con: containers that should appear empty will never appear as they will be rendered. but without something inside it then it's very hard to click inside it to select it?
gutenburg has an extra button inside containers (only sometimes appears? only when empty?)
Quanta doesn't have a design for this as it is not not designed to support container blocks.
In most cases you would click on a block inside the container and add before or after
But what about when the container is empty?
Ways to support it could be