These days software has been done a lot. You should be able to find others who have done similar things and learn lessons from them. Considering microservices - there are lots of people who have done them and can tell you what worked well and what didn't. Considering using QT - lots of others have and can give you ideas. Considering writing your own framework - there are lots of others: look at what they do good and bad.

If you are doing a CRUD web app for a local small business - there are thousands of examples. If you are writing control software for a space station - you may not have access to code from NASA/Russia/China but you can at least look at generic software that does the things you need and learn some lessons.