I've been scaling back too so that's been working for me (mostly).

One year (I think it was 2018 when TCJA started) I sent an email to all of my "last minute" clients telling them that I wasn't doing last-minute work any more, if they wanted their returns prepared by me they had to have substantially all of their data in to me by 3/15.  Basically I gave them enough rope to hang themselves.  Then when they contacted me in April I politely gave them the IRS and VA sites for making their own extension payments and told them they would need someone else to file the return.