I am hoping there is a simple config/number change in the grub
config files, but I can not find it in the doco I've read.

In the past, the list of kernel images just grew each time you
loaded/updated the linux-image files. But the current system
automatically trims it to just two, with normal and recovery versions of
each.

The reason I want to do this is to lad step through some of the 5.*
kernel to see if any of them now give any support to my AMD RX 5700* XT
gpu card that has been unable to be used(unless I want a single screern
in vesa mode).

LS: At this stage the hardware is correctly identified by various
hardware programs with mirrored dual screens during boot up, but the
between Xorg, Mesa & Vvulkan, which supposedly make it work, I just get
a VESA single screen.

My tip is never to but any AMD 5700 card. My 5700 HD never worked
reliably under their proprietary driver and it was years before the
Radeon driver was able to support it.

T.I.A.