I’ve found some examples like:
Alles ist richtig.
Meine Familie ist sehr geil.
Are there other examples of same usage?
I see this is going to be too long for a comment.
Having a single word describe more than one thing does not mean the word is plural. Most of the time plurality conforms to what the word describes in its most direct sense.
Here we have multiple people being described.
Here it refers to a situation or just … everything; not two or five things in particular.
Here the subject consists of two persons so we use plural.
Now it gets more subtle. Although a herd of sheep consists of multiple sheep, we describe the herd as a whole. We don’t mean a small subset of sheep but address all of them at the same time. I don’t know if this makes sense (in particular the difference between this and the first example).
It’s more or less the same with Familie. That word is used to address a group of people that belongs together in a very rigid fashion.
Familie and alles are not plural words. They define single entities. So, using the singular conjugated verb is perfectly right in these cases.
The confusion about this for English speakers comes from a difference between English and German grammatical logic.
In German verbs conjugate for the grammatical number of the noun, even if that singular noun represents a group of people or things.
In English it's common to conjugate according to the extrapolated number the noun represents. It's probably incorrect on some level but extremely prevalent.
So in English you might say the family are because "the family" is more than one person, but in German you say die Familie ist because you are talking about one family.
In this article from The Guardian, they use England are even though there isn't more than one England, because they are talking about the English team of players. You don't do this in German.