To search specifically for 8 band imagery, use CLI as well.
In this case, please make sure to use --item-type PSScene as 8 band imagery is only available as PSScene item type. You can also include an --asset-type if you wish. Try something like the following:
planet --api-key <key> data search --item-type PSScene --asset-type ortho_analytic_8b --date acquired gte 2021-06-01 --date acquired lt 2022-01-15 --geom your/directory/AOI.geojson --sort acquired asc
CLI will return imagery over your AOI, including download permissions. If you don't have access to 8 band imagery, please reach out to Planet support or your CSM at Planet, so that we can enable it for you. Please note, 8 band imagery is available to customers who have purchased access to PlanetScope.