You have to look at card texts as information blocks that you can take apart and rearrange.

“when” - this implies an ability that triggers once, like [[Aracokra Sneak]]. The alternative would be “whenever” for repeated use, such as [[Abomination]]. When combining a one-time-trigger with a multi-time-trigger, “whenever” is used, I.e. [[Aerial Extortionist]]. “When” or “Whenever” can also be specified, for example with “for the first time”. But all of this already covered by searching for “when”. If you want to search for specific conditions, you can search for “if”.

When looking for cards, just look at card texts this way and you will quickly learn how to read them and how to narrow your search. Then go to scryfall search reference and learn how to use search tags for professional search: https://scryfall.com/docs/syntax#oracle