Overwrite content in Redshift using Glue

If you mean upsert, there is a workaround solution, have glue insert all rows into a staging table and then perform a upsert/merge outside of glue.

Use a Staging Table to Perform a Merge (Upsert), https://docs.aws.amazon.com/redshift/latest/dg/c_best-practices-upsert.html

There is also a big data blog talking about upsert into Amazon Redshift using AWS Glue and SneaQL, I haven't tried, however, sounds cool to give a go. https://aws.amazon.com/blogs/big-data/upsert-into-amazon-redshift-using-aws-glue-and-sneaql/