How to sort the indices through it's property in multi Indices approach

[Muna]

Hi, below is my query multi Indices approach. here i want to sort the 'abc_class' by it's "classId" .

tried applying sort at the beginning it's not working. please advise.

GET _all/_search
{
"query": {
"bool": {
"should": [
{
"bool": {
"filter": [
{
"terms": {
"_index": [
"abc_class"
]
}
}
]
}
}
]
}
}
}