The number list is how markdown works. You can enter all 1’s and it will automatically create ordered list.
Handy when you may need to edit list items, as you dont need to renumber even in plain text.
Markdown spec should allow for explicit number by using a bracket ‘)’ instead of a dot, but it may not work everywhere.
Let’s give it a go

3) start from 3  
1. Then  
1. Continue  

3. start from 3

1. Then
2. Continue