It's not every day players get a new sci-fi RPG, but quite a few are now on the horizon, two of which are Bethesda's Starfield and BioWare's Mass Effect 4, Both of these games have huge expectations behind them, because of the pedigree of the developers in Starfield's case and because of the history of the franchise in the case of Mass Effect 4.
Starfield, a day one title on Xbox Game Pass, was announced well before Mass Effect 4, and the fact that Mass Effect 4 is on the horizon means that Starfield is going to have some competition that wasn't on the board, initially. That isn't necessarily a bad thing: competition breeds innovation, and both games might be better than they would be otherwise because of it. That said, the style of RPG that Bethesda and Bioware make are vastly different, so these games aren't necessarily going to step on each others' toes.
Bethesda RPG vs. Bioware RPG
In the past, Bethesda has always made primarily 1st-person, open-world RPGs where the player has almost complete and total freedom over what they do in the world. There aren't generally many cinematic cutscenes, and dialogue scenes may or may not actually involve a player's character having a voice. These games attempt to immerse players by making them truly feel like a person in the world that the game has created, albeit a person of significant power or importance. Some reports indicate that Starfield may be stepping back from this approach a bit, but for now, that's not confirmed.
Bioware doesn't always take this approach, instead generally favoring a third-person view. Characters still have huge decisions to make (just take a look at some of the hardest decisions in the Mass Effect franchise), arguably more important decisions to the surrounding world than many decisions made in Bethesda RPGs. But, players are more locked into a specific role in these games, as opposed to the freedom presented in a Bethesda RPG. This role can be acted in just about any way the player decides, but the story of the game is focused around the player functioning in that role.
Both of these styles of RPGs can make great games, as both of these companies have done so in the past, they just feel pretty different. While there is some overlap there, the audiences for these games are going to vary a bit.
Mass Effect 4 and Starfield Will Make Each Other Better
The good news is, the fact that these games are likely going to be competing with each other means each is going to have to strive to be better than the other; this will be especially true if the Starfield and Mass Effect 4 release dates happen to be anywhere close to each other. Given so little is known about their development, there's certainly a possibility. While some players are certainly going to be grabbing both, others are going to be forced to pick one over the other, at least right at release.
This is going to force innovation onto the developers, if the game wasn't going to be especially innovative already. These games have some inherent advantages and disadvantages right from the start: Starfield is the beginning of a new IP, meaning there aren't necessarily any expectations of the game-world, and Bethesda is free to make of it what it wants. On the other side of that, Mass Effect 4 is part of a well-established and well-loved series. There are expectations of the story and the world here, but that can be a bit of a blessing, too. If the game lives up to that standard, it's going to have the fans that have loved the series for years already onboard, whereas Starfield is looking to start something new (and, incidentally, Starfield's procedural worlds need to learn something from Mass Effect).
Both of these companies have released quite a few very well-received games, and both of these companies have released some games that have been not quite as well-received, too. Fallout 76, Mass Effect: Andromeda, and Anthem were all heavily criticized on release, shaking the faith that some of the players have in these studios. Starfield and Mass Effect 4 are, in many players' eyes, the redemption arc for these companies. The fact that these games could be releasing so close together means that some extra pressure has been added to a situation that already had quite a bit of pressure to begin with.
For now, fans are just going to have to patiently wait for more information on both of these games. Starfield is rumored for a 2021 release, though that's yet to be confirmed and seems really unlikely.
Starfield and Mass Effect 4 are in development.