I know this thread is a few months old, but to make it clear, the newer devices are HDMI only. The only current Roku models that support the 4:3/16:9 setting are the Express+ models 3710 (released 2016) and 3910 (released 2017), which were discontinued in 2018/2019. I’ve had the latter model for two years since February 2020 (bought from Walmart online), and it, along with the former, was the very last model with the analog A/V outputs and the 4:3/16:9 setting. With HDTVs being sold in retail markets these days, analog TV sets only being found in used markets, including eBay, and ATSC 3.0 coming in the next few years, I highly doubt any of the major players manufactured in the future will have analog outputs and a 4:3/16:9 setting. There may be some generic unlicensed Android boxes with analog outputs, but I do not recommend those at all.
I’m into videotapes and old electronics stuff, including extenders, converters and analog 4:3 TV sets (which are obsolete these days), and Miss Bianca is my favorite character in Disney’s The Rescuers (1977) and its sequel, The Rescuers Down Under (1990). I am not a Roku employee, only a user like you. ~ Jordan
Roku Express+ 3910X