Creating 'index' content views for L1-LX within a taxonomy
There are features in Views concerning taxonomy hierarchy, displaying terms with depth, you should look into it. There is also Group by field option under Format in Views where you can, for example, group by Parent field (Parent of the Taxonomy term). You may need to add a Relationship for the Taxonomy field first before you can see those extra Fields/Filters. Contextual filter with depth might also be useful. 
You should look into displaying Menus with depth, since each Taxonomy Vocabulary already has a Menu block. You can learn more about it here: Primary and Secondary Navigation in Drupal 8


Generally speaking, you want to get to a point where you have correctly nested HTML list items. Then you can use CSS to adjust the numbering to go into levels 1.1, 1.2 etc. 

Or if that numbering is so important you could add a field for it on your Vocabulary, so each item has that textual bit of data associated with it (not numbers because the sorting won't be correct, you want 1.10 > 1.1). Sorting in Views can still be done with the term weight (the sorting you saved in Taxonomy).