It depends.
The IRS issues a lot of refunds within 21 days, but it has been taking longer with the stimulus payment being issued in addition to the tax refunds.
IRS processing time and refund status
The online link is your best option to track your refund. I have attached a link with more answers from the IRS as to why your refund may be taking longer to process.
Federal refund questions
As you mentioned in your question, the IRS operations are limited during the Covid-19 pandemic. Attached is a link with more information as to what departments are available to contact at the moment.
IRS operations