I thought I'd do a bit of back-ground sense-checking on the 'bigger' clubs that have fallen in to level 3 recently. Some have had a yo-yo existence for a while, some have over-achieved in recent years, but some I had forgotten about falling as low, as recently, as they did,
2017-2018 Blackburn Rovers
1989-1992, 1994-1995 Birmingham City
1990-2013 Bournemouth
1992-2002, 2003-2004, 2006-2011 Brighton and Hove Albion
2009-2012, 2016-2019, 2020-? Charlton Athletic
2012-2020 Coventry City
1983-1984 Derby County
1990-2005, 2020-? Hull City
2019-? Ipswich Town
2007-2010 Leeds United
2008-2009 Leicester City
1998-1999 Manchester City
2005-2007 Nottingham Forest
2009-2010 Norwich City
2011-2017 Sheffield United
2003-2004, 2010-2012 Sheffield Wednesday
1996-2001, 2006-2010, 2015-2017 Millwall
2011-2015 Preston North End
2009-2011 Southampton
2018-? Sunderland
Inception-2003, 2015-2016, 2017-2018, 2020-? Wigan
1985-1989, 2013-14 Wolverhampton Wanderers
I have probably missed a few that others will think are worth including, but hopefully this shows that no team is too big to fall to the third tier and that once down here, it can be very difficult to get out. No 'god given right' in the history of football I'm afraid.