[Yum] upgrade/update redhat 7.x->8->9->fedora

[mike andrews]

stupid newbie question:

i have a redhat 7.x system i updated with yum for the first time last
night, and it seems like it was a success, with lots of packages being
updated. the system still works :-)

now i'd like to 'move forward' if possible, to packages from redhat 8,
then 9, then fedora 1 and 2. is that something one can do solely with yum?
if so, how would i do it? would i just add some of the appropriate public
yum repositories to my /etc/yum.conf and type 'yum update'? or would 'yum
upgrade' be more appropriate? i've never used the 'upgrade' command
before.

thanks, mike (i haven't subscribed to this mailing list yet)