how to pass other;s fields paramter or metadata while uploading multiple documents

Hi,

I am using this reference

https://sharepoint.stackexchange.com/questions/154472/upload-multiple-files-using-rest-api

to uploading multiple documents into library,  its working fine

just let me know 2 things

1)how to add other's fields while uploading file. I have 3 columns

1) flag,2)departname,3) status , I want insert values into this columns with documents)

2) only allow to upload pdf files ,(need to validate file extension before uploading)

(e.g) while uploading single file using below reference we can add columns  values into this method "updateListItem"

https://docs.microsoft.com/en-us/sharepoint/dev/sp-add-ins/upload-a-file-by-using-the-rest-api-and-jquery

kindlu guide me to pass lookup value and others columns values while uploading multiple files.

Thanks