how to upgrade ClickHouse version upgrades ？

[jessezax]

just modify the image and apply？

[jessezax]

Will this lose data？

[Slach]

If your cluster has properly configured CSI / volume provisioner data will not lose, when define in your kind: ClickHouseInstallation something like that

spec:
  templates:
    volumeClaimTemplates:
      - name: data
        reclaimPolicy: Retain
        spec:
          accessModes:
           - ReadWriteOnce
         resources:
           requests:
              storage: XXXGi # how much data size you need to storage data
   defaults:  
      dataVolumeClaimTemplate:  data   

after it, you can update image: in your podTemplates section

Moreover, will useful look to https://github.com/Altinity/clickhouse-operator/blob/master/docs/custom_resource_explained.md to understand format for chi custom resources