Can we Upgrade the old project version to the latest version 0.69 without adopt new architecture?

After reading some docs about updating from the versions that I had (0.67 -> 0.69/0.68) I read this post from the React Native page (An update on the New Architecture Rollout). This post is about the new release that fully introduces the new Architecture, in this post you can see that it is optional to use the new Architecture only by changing some variables.

So, to answer your question, you can update to RN-0.69 and keep the old architecture and if you want to try the new architecture you need to change some variables for iOS and Android.