As of today, Oct 12, 2020, there is no reprieve from late filing penalties for returns due Oct 15, 2020 and filed after that. This could change. Your client could possibly get penalty waived for reasonable cause.

Some suggest marking COVID-19 Relief at the top of the return or as statement.

Whether you can, and how to do this in ProConnect Tax, I don't know. I think it may have been discussed in the forum.