Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
The Tubi channel is now carrying a lot of the news stations. You can install Tubi from the Roku Home Screen...Streaming Channels...Search Channels...Tubi
To access Fox13 Tampa Bay from within Tubi, navigate down to "News on Tubi" and then scroll to the right until you find "Fox 13 Tampa Bay". For some reason it did not come up using the Tubi Search feature so had to manually locate it from within the "News on Tubi" category.
Another good Channel/app is Haystack News, but again, Fox 13 did not show up as available but other Florida stations did.
I found this link after locating Fox 13 Tampa in Tubi, so looks like may be limited to watching over-the-air (OTA antenna), Tubi TV, or watching online at their website and then casting it or using a HDMI cable to your TV. May be a chance that included with some paid subscriptions to Hulu or the like that offer packages with local channels, but the above ways seem to be the free options available to you.
If you want to watch all the content that the Fox13 channel has (not just news), then can maybe look at the Locast Channel if OTA(antenna) option isn't desirable for you. This channel streams local channels.