NGINX https config for a single domain with PHP app on Debian 10 using Letsencrypt certificate

domain.conf

server {
  listen 443 ssl http2;
  server_name example.com;

  root /var/www/app;
  index index.php index.html index.htm;

  ssl on;
  ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
  ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;

  add_header Strict-Transport-Security max-age=15768000;

  ssl_session_timeout 5m;

  ssl_protocols TLSv1.2 TLSv1.3;
  ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-G;

  ssl_prefer_server_ciphers on;
  ssl_dhparam /etc/ssl/dhparams.pem;

  # OCSP Stapling
  # fetch OCSP records from URL in ssl_certificate and cache them
  ssl_stapling on;
  ssl_stapling_verify on;
}