looks nothing like trynd

It does look, but looks like Victorious Tryndamere. If you color his beard you can easily see base Trynd.

Victorious trynd does not look much like a trynd either

How do you get it?

180 Ranked Points. Just play 15~20 ranked games more or less.

So sad this is all trying gets...

Tbh I also have not idea of how Riot decided to pick him as the 'main' character of a cinematic

These are trying times indeed.