Well, ionic build doesn’t actually do the building of the web app. It hands off the build to whatever underlying stack you are using. Angular, the Angular CLI, Vue the Vue CLI or Vite, and similarly with React.
I am not familiar with Angular or React, but I would assume any stack these days should be creating unique file names per build so the cache gets busted.
I already gave you a solution to handle index.html.
In regards to -
that was suggested to handle when users leave your app open in the web browser for days on end, they never refresh getting a new index.html file. So, alerting them that there is a new version is a good option.