EA Sports have confirmed that FIFA 21 will be released on 06 October 2020 worldwide on all plateforms. However, EA are yet to confirm the availability of official demo which is usually released 20 to 25 days before the official games release.
FIFA 21 Demo Release Date: Looking at the past few years we can see a pattern where EA release the demo atleast 3 weeks before the official games is suppose to be released so for 21 edition we are looking at second week of september and definitely before 20th September.
For FIFA 20 last year, the game was official released on 27th September and the demo was out by 10th September. This year however due to covid-19 pandemic EA pushed the release date 10 days which means we will be getting FIFA 21 demo between 15 to 20th September 2020
How to download free demo of FIFA 21: Once the demo is released by EA Sports, it will be available in online stores of both PS and Xbox consoles. The demo is usually around 10GP and it is free to download regardless you have pre-ordered the game or not. So its a good way to gauge your expectation from new game and the reality of what you getting.