since you render your quarto with LaTeX to PDF, we can add a cutom header to overwrite the enumerate (1.,2.,3.,...) and itemize (bulletpoints) like this:

---
title: "test list"
format: 
  pdf:
    include-in-header:
      text: |
        \usepackage{enumitem}
        \setlist[itemize]{topsep=0pt,itemsep=0pt,partopsep=0pt,parsep=0pt}
        \setlist[enumerate]{topsep=0pt,itemsep=0pt,partopsep=0pt,parsep=0pt}
---

1. First
2. Second
    + sub 1
3. Third