IRCNow

First please read openbsd:www:openhttpd and openbsd:php

server "example.com" {
        alias "www.example.com"
        listen on * tls port 443
        tls {
                certificate "/etc/ssl/example.com.fullchain.pem"
                key "/etc/ssl/private/example.com.key"
        }
        location "/.well-known/acme-challenge/*" {
                root "/acme"
                request strip 2
        }
        location "*~" {
                block drop
        }
        location match "/kb/data/" {
                block drop
        }
        location match "/kb/conf/" {
                block drop
        }
        location match "/kb/bin/" {
                block drop
        }
        location match "/kb/inc/" {
                block drop
        }
        location match "/kb/vendor/" {
                block drop
        }
        location "*.php" {
                fastcgi socket "/run/php-fpm.sock"
        }
        directory {
                index "index.php"
        }
        root "/htdocs/example.com/"
        connection max request body 104857600
        hsts preload
        hsts subdomains
}

Edit /etc/php-7.3.ini to allow larger file uploads:

post_max_size = 100M