change template plugin

Hello!
Prompt please function, with which I can change the template in the plugin, and on what event?

I need to change certain events website template, not from the administration panel, namely, the php-script.

is it real?
thanks for advance

I think you want one of these. I'm not sure which:

OnHandleRequest — Fires when any request for a resource is received in the front end.

OnWebPageInit — Fires after determination that the site is online and the requested resource is located.

OnLoadWebDocument — Fires after the requested resource is loaded, but before it is parsed.

OnParseDocument — Fires just before the MODX tags are processed.

And one of the following (again -- not sure which, but I think it's the first one) to test them:

thanks for help, it's work OnLoadWebDocument.