Yes, but it’s complicated. If you have more than one Switch console—a full-size version connected to a TV and a Switch Lite for a kid, for example—you can download every game and piece of downloadable content you’ve bought on the Switch eShop onto both consoles. But when you sign in on more than one Switch with the same user account, Nintendo forces you to designate one Switch as the “primary” console and any others as “non-primary” consoles. Non-primary consoles are subject to a number of restrictions, which Nintendo fully outlines here (you see these kinds of restrictions when you own multiple Xbox or PlayStation consoles, as well).
In short, non-primary consoles require an internet connection to play any downloaded game (or any game for which you’ve bought downloadable content, even if the game itself is on its own game card). If you have no internet connection, or if someone is playing any downloaded game on the primary Switch, you can’t play on the non-primary console.
And although any account on the primary Switch can play any game downloaded by any other user account, downloaded games on non-primary consoles can be played only by the user account that originally purchased them. So if you want to play some local multiplayer in Mario Kart 8 Deluxe or Super Smash Bros. Ultimate, for example, you need to own two copies of the game.