- Don't default to "Agile" (or be fully "Agile" for that matter)
- Don't default to Typescript (or any technology for that matter)
- Don't default to TDD (or any dev methodology for that matter)
- Don't default to linters and bundlers (or any intricate tooling for that matter)
- Don't default to complicated infrastructure
A friendly PSA that you can still, in the year of our lordt 2019, create a static site with an HTML file deployed to shared hosting over FTP. You could also create a dynamic site with some PHP thrown in there.
Reach for the minimal process, tech, methodology, tools and infrastructure you need to get the next X pieces of work done, and complicate things only if the pros outweigh the cons.
I'm not picking on you specifically blobs, I'm sure you walked into an organization that employed all these things with seemingly no good reason. The thing is, there's always a reason, it just might not be a great one!
That said, if your goal is to estimate things more accurately, you might need to spend a little more time with your coworkers to define as many unknowns as possible.