Every time I draw a trendline, I see someone else draw it slightly different.

They are completely subjective.

Take BTC for example, it's breaking out of a downtrend from the all time high, right?

Well, not if you draw your trendline like this:

(Source: https://twitter.com/koreanjewcrypto/status/1262003953258070021)

So, which is it, did bitcoin break out or is it at the the trendline now?

See what I mean?

Do you draw your trendlines by the wicks or the candle bodies, or both?