Yes, that is possible!
Many (although not all) of these monitors have a 9-pin port often labeled "TTL" or something. You can connect CGA and EGA cards directly to those.
As for VGA, that can be made to work with RGB SCART monitors and TVs as well, but it will require a scan doubler an active adapter.
However, some VGA cards can be programmed to directly output the lower 15kHz frequency supported by these monitors, without needing a scan doubler an active adapter. In that case, a passive VGA to RGB SCART cable would suffice. (Well, that and the software to switch the VGA card in the required mode.)
If you search a bit on this forum, and google (or DuckDuckGo) a bit on-line for keywords like "VGA", "RGB SCART", and "scan doubler", you'll find plenty of information.
These are always fun projects. Good luck and have fun! 😃
Also kudos for fixing those CRTs. They're all getting rarer these days.
EDIT: sorry, I indeed got it the other way around by erroneously mentioning a scan doubler as a solution. Thanks, Grzyb.