Increase innodb_buffer_pool_size on MariaDB Galera 10.2.25

We have planned to increase innodb_buffer_pool size from 120 GB to 180 GB on 3 node MariaDB Galera Cluster.

Recently we changed value of innodb_buffer_pool dynamically on ONLY first node and stopped all Nodes.

After restart of all Nodes , we found new value didn't reflect .

We have changed the execution steps , Kindly guide on the steps

1) Stop MariaDB Galera on all three Nodes.

2) Edit my.cnf configuration file on all three Nodes with new value of innodb_buffer_pool
( No need to dynamically change innodb_buffer_pool value on all 3 nodes )

3) Start MariaDB Galera Cluster on all three Nodes in proper sequence.

Kindly advise on the steps prepared.