Hi,

Try like following

this._rpc({
    model: this.fields[this.parent_name].relation,
    method: 'search_read',
    domain: [[this.parents_name, '=', recordId.id]],
    fields: ['id', 'name'],
    sort: "",
}).then((result) => {
    if(result.length) {
        // do somthing
    } else {
        // do somthing else
    }
})

Regards