change content type for specific uri in http response

Not sure how exactly this would help if response is not coming in json format from the server. but you can try below.

when HTTP_REQUEST {
set var_uri [HTTP::uri]
}
 
when HTTP_RESPONSE {
if { $var_uri eq "/.well-known/apple-app-site-association" } {
log local0. "match found $var_uri"
HTTP::header replace "Content-Type" "application/json"
return
  }
}