Recently I have been working on a project that requires GTM, GA & GO to be installed on a website.
Is there an optimal way to install all 3 onto the website without requiring copying of 3 individual code spinnets?
If we do require 3 individual code spinnets, What is the correct order to place the spinnets?
Not having to install multiple separate snippets is pretty much the point of a tag management system.
Create a Google Tag Manager Container and install the code snippet in the head of your page (that is the recommendation, but it will work pretty much everywhere else).
Then go to your container settings. In "Tags", click new. You will see tag templates for both Google Analytics (both Universal Analytics and GA4) and for Google Optimize (Documentation for Optimize with GTM is here, although it is slightly confusing). Basically you create a tag with the respective template, drop your tracking ids in, create a trigger that says when the tag will be executed and then publish your container.
You might want to have a look at the online courses Google offer for GTM: https://analytics.google.com/analytics/academy/course/5 to make best use of GTM.