@Toi there are lots of tools/ways to expand the literal

\n \t

into newlines and tabs if you can't get insomnia to output the raw data. here's an example using printf:

$ schema="definition platform {\n\trelation core_module: plan#subscriber\n}\n\ndefinition plan {\n\trelation subscriber: company#employee\n}"; printf '%b\n' "$schema"

definition platform {
    relation core_module: plan#subscriber
}

definition plan {
    relation subscriber: company#employee
}

or (ab)using `jq`:

$ echo "definition platform {\n\trelation core_module: plan#subscriber\n}\n\ndefinition plan {\n\trelation subscriber: company#employee\n}" | jq -R -r "${1}"

definition platform {
    relation core_module: plan#subscriber
}

definition plan {
    relation subscriber: company#employee
}