First, make sure that apps are included in your results.
Include apps in Spotlight results
- Open System Settings
- Click on Spotlight
- Scroll down to the Results from System section
- Set the toggle for Apps (above the red box in the screenshot below) to ON

If that does not work, then rebuild the Spotlight index for the above steps to work properly.
Rebuild the Spotlight index on your Mac - Apple Support
If that still doesn’t work, Copy/Paste this into Terminal. sudo will ask for your password. Just type the password and hit return. It won't show anything on screen. Those two commands essentially nuke all the Spotlight records then force a reindex. You may need to restart or log out/in after running the commands.
sudo mdutil -X /; sudo mdutil -i on /
Note that Spotlight re-indexes your Mac after a macOS update, and this process can take some time.
More info from Apple: About Spotlight indexing and search results on Apple devices - Apple Support