I had to do the same. I wonder why it's difficult for the Mac OS/App Store to prompt us for updates for this stuff. Sure I get update notifications for the VOX audio player ASAP, but Apple's flagship apps? Nope. Actually I doubt these are Apple's flagship apps, I think they generate less than 5% of their software revenue. SOURCE: My ass.
If you are not seeing the updates using the usual method when you run software update, then select in the top menu "reload page" and the app store updates should appear. If you are still on Mojave, you will not see an update for iMovie as the last two updates for that require Catalina.