I would like to add tags to a Amazon Rekognition Custom label model is this possible?

Yes this is possible and you can use the Rekognition console to add tags to models, view the tags attached to a model, and remove tags. Could you please check this AWS well detailed documentation to guide you in doing this :- https://docs.aws.amazon.com/rekognition/latest/customlabels-dg/tm-tagging-model.html

Hope it clarifies and if does I would appreciate answer to be accepted so that community can benefit for clarity, thanks ;)