In the alerting, I found that many contact points (such as Discord, Telegram) have Optional Discord/Telegram settings to use custom message templates. But LINE has not Optional LINE settings to do it. Could LINE use custom message templates now? If not, is there any plan to make it possible? Thanks!
Did you find the solution? I have the same question now 
Hi all,
Well, there are some significant improvements made in the area of Alerting in ver. 9.3.x which are also described in the release notes.
Also, this might not be related to the question but just wanted to share this very active post where users have been asking a lot about alerting and you may find some more valuable information there.
I hope this helps.
Hi! Grafana does not support custom templates for LINE at present. It would be great if you could open an issue on Issues · grafana/grafana · GitHub.