This is where the trailing stop will move around according to a set percentage difference from the previous closing value. This allows you to say "If the current bar moves x percent, then stop". The script I've made here is a simple version of that with a few options for smoothing and setting the percent change.
Disclaimer: This is not financial advice, please do your own research before making any decisions.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.