In both the browser extension and mobile apps of the Phantom wallet, you can view the current top tokens by visiting Phantom's Explore section. To get here, first select the globe 🌐 icon along the bottom of your wallet view and then clicking on Tokens.
Tokens can be sorted by Gainers, Losers, Volume, and Market Cap. They can also be filtered by the specific networks they reside on (only tokens that are on networks that Phantom currently support will be listed.)
Clicking on any of the tokens of your choice will bring your directly to the in-app swapper to conduct a trade.