All foreigners whose residence permit expired during the state of emergency may stay in the Czech Republic for additional 60 days after the end of the state of emergency (17th of May 2020). This applies both to those who require a visa and those who are visa-free. Expired Schengen visa and visa-free stay does not need to be extended. Instead a so-called “exit stamp” will be issued at the time of departure. When exit stamp is issued a foreigner must leave the country within 24 hours.
More information can be found on the MOFA website.

•  https://koronavirus.mzcr.cz/en/list-of-countries-according-to-the-level-of-risk/

Work permits which expired after March 12, 2020 remain valid until November 11, 2020 as long as the employment contract is extended for the same period of time. This applies to holders of following visa types:

• Short term schengen visa for purpose of work
• Short term visa for purpose of seasonal employment
• Long term visa for purpose of seasonal employment
• Special work visa

All above mentioned foreigners must leave the country by November 11, 2020
 

More information https://www.mvcr.cz/docDetail.aspx?docid=22261607&doctype=ART