Error 414 URL too long- jenkins/nginx

We have deployed jenkins(image) as k8s resource. While triggering pipeline as post request (URL+Variable) that is 8192 long approximately. nginx(jenkins server) is rejecting it with 414 URI Too Long . I can see the request in the system logs and pipeline is not initiated.
I have tried to update the nginx configuration using config map, but no luck. I have added below params -

client_header_buffer_size 5120k;
large_client_header_buffers 16 5120k;
 When I add above , my nginx-pod is not getting started(crashloopbackoff)error.

Also, I tried changing “/etc/nginx/nginx.conf” with above params in pod(nginx), but no luck.