Depends on the size of the data and types of queries, I suppose.
Elasticsearch is pretty nifty (especially for a single server setup, and I would personally reach for it, if it fits my budget). There’s quickwit.io (beta?) if you prefer serverless / stateless. Snowflake Search (or delta.io) if your data is in PB/ZB scale. If you’re merely looking add search to your docs or website, there’s algolia.com and typesense.org. Even SQLite has FTS (full text search), which could be useful.
If you are searching logs, then see: fly-log-shipper to NewRelic / LogDNA / HoneyComb / Logflare etc, fly-log-local to Loki, or roll your own backed by SQLite.