I'd like to search all post from a particular account by specific word. Similar to twitter advanced search =
(key) (from:joinmastodon)
I haven't found the way how to do it.
Any advice would be appreciate.
This is not possible (intentionally / by design).
Mastodon supports search on hashtags and user names on a local instance, or (if ElasticSearch is available and the instance administrator has enabled it) for a user's own content in full text, but not across the whole database. See the documentation:
Mastodon supports full-text search when ElasticSearch is available. Mastodon’s full-text search allows logged in users to find results from their own statuses, their mentions, their favourites, and their bookmarks. It deliberately does not allow searching for arbitrary strings in the entire database.