Find all sql statements larger than X bytes?

Can any of the tools in Percona Toolkit log all SQL queries where the statement text is larger than a certain size?

I don’t think there is any filter exists to log queries on basis of query size. However, queries do log “Bytes Sent” information against each query which is amount of bytes sent for the result of the query. Along with that, you can log extended information and stats for Percona Server in slow log as described in https://www.percona.com/doc/percona-server/LATEST/diagnostics/slow_extended.html

You can use pt-kill with a custom filter: https://www.percona.com/doc/percona-toolkit/LATEST/pt-kill.html#cmdoption-pt-kill-filter