I just upgraded from Imac to M1 Imac. My second monitor wont work. I bought an adapter cable, so I am connected
VGA-Thunderbolt 2(display port)-thunderbolt3-Imac. Three cables involved. I get no signal to the monitor. Should this work?
Probably not. You'd be better of with a (direct) USB-C to VGA adapter.
Most likely your "Thunderbolt 2 to VGA adapter" is just a
MiniDisplayPort to VGA adapter - these are sometimes confusingly sold as "Thunderbolt 1/2 compatible" and while they'll work with the TB1/2 ports in older Macs (which also supported DisplayPort & HDMI) but not with (most) TB3-to-TB2 converters.
Also, though, if your monitor has
anything better than VGA - i.e. DisplayPort, HDMI or even DVI - that, with the appropriate USB-C-to-whatever cable, will give you a batter picture.