Nearly everyting in this json can be parsed using JsonUtility by just creating the correct nested classes. As a small pointer everything { } will become a class with [serializable], everything will become an array.
As far as I know though [“4”, {…}] is not supported in the default unity serialization as you can not mix types in an array (e.g. string and class in this case). So if you cannot affect the structure of the json (supplied by an external party) you will need to look at alternative json parsers like the popular Json.net.
And please edit the post with code tags and a json formatter to make the json readable.
Json.net is available in the assetstore https://assetstore.unity.com/packages/tools/input-management/json-net-for-unity-11347 and has a lot of documentation/examples you can find on the internet.
With this you should be able to gradually built a parser for your json except the [4, {…}] part whch will likely require some advanced stuff I would need to read up on too.
For the first step don’t worry about it though and just get everything else to parse little by little. That should give us a good starting point for improvements and adding the [“4”, { }] stuff.