innodb buffer pool size not changing
Repeating the above comment to provide an "answer" for this question:
The config file /etc/percona-server.conf.d/mysqld.cnf was not being included in the standard "global config" file, commonly known at /etc/my.cnf. @OP added !includedir /etc/percona-server.conf.d to the end of the global config and then the changes were visible upon restart of MySQL.