I had a hell of a time getting Drupal 9 to show template changes. There are other posts and such on the interwebs about this, but none worked. Perhaps it was the lando configuration. Here are the changes I needed to make. Change the following in your services.yml (this should be located in the sites/default

The exact lines are subject to change of course, but these are where I found the following in the services.yml.

line 74:

    debug: true

line 83:

    auto_reload: true

line 94:

     cache: false

That's it! Happy Drupal Developing (if there's such a thing).