Having menus rendered on a site in Drupal 8 is pretty simple. Most of the time this can be accomplished with site building, in a few clicks. And if you need some more advanced features on top of what the Drupal 8 core has, you can also have a look at modules like Menu Block, or have a look at this (a bit outdated) contributed modules for menus page.
However, you may have some special requirements, for example, to display some small portion of a menu inside the template of a node. There is no simple 'site building' solution for that. You most probably need to code a bit.