If you choose to have the refund DD to your checking account directly from the IRS then that is how the stimulus check will also be sent ...
The easiest way to find out is to look at your Filing Instructions document (or Electronic Filing Instructions document), which prints out as part of your tax return paperwork. The direct deposit information will display routing & account number. Instructions on how to print (or simply download and look at the documents):
https://ttlc.intuit.com/questions/1900831-how-do-i-print-a-copy-of-my-tax-return-after-filing-for-my...