I mean, grep will find content in those sections but won’t be limited to those.

To limit it, if you devote the first 3 lines to title, summary, tags

You could extract the first 3 lines of each file and grep those.

If not, if they have a prefix,

    title: 
    summary:
    tags:

You could grep those first then grep the output.

    grep -E ‘title:|summary:|tags:’ | grep ‘query’

A simple script can be built.