Adding data after csv filter from rest api using http filter

Hello, i have 2 file: csv and json. i wanted to read the json file to get access token.
here is my config:

input {
  # Open csv from path
  file{
    path =>["/some/path/log/*.csv"]
  }
}

filter{
  # Parse csv input  
  csv{
      columns => [
      "Local_IP",
      "Local_Port",
      "Remote_IP",
      "Remote_Port",
      "Protocol",
      "First_Seen_At",
      ]
      separator=>','
      skip_header => true  
  }
  date{
      match => ["First_Seen_At", "UNIX_MS"]
  }
  
  # Call rest api using "Remote_IP" field
  http{
    url => "https://www.example.com/api/%{Remote_IP}"
    verb => GET
    target_body => some_body
    headers => {
      "Authorization" => "Bearer %{accessToken}"    }
  }

output {
}

I want to load the json file and set %{accessToken} field. How do i do this?