You can't e-file it today. It has to be mailed and postmarked by today in order to get an extension to 10/15. Print it from the link below and get it postmarked and in the mail today! See Further Tax Filing Extensions Available
You can e-file your tax return (Form 1040) until 10/15/25. If you are trying to file an extension through 10/15, you have to file the form by mail; it can't be e-filed now and it has to be postmarked by tomorrow (5/1).
If you file your return by 05/01, the IRS will not impose a penalty. It is automatic; no Form 4868 needed.
Form 4868 and instructions included