Im a Shimano guy so I can only speak to that side of the house.
GRX series is there gravel specific line including a Clutch rear der. My 2021 Trek Checkpoint ALR5 came stock with this setup (mechanical not di2). I think its equivalent to Road Ultegra level which is pretty good value for the money.
instead of me guessing my first google result came up with this article which seems to cover all of it for your reading pleasure. As you can expect the different manufactures mix and match to play with price point on the bikes. before Gravel specific drivetrains came out I think most of the bikes just came with road setups but I could be wrong.
Here’s everything you need to know about the GRX line-up, including what’s available, upgrades and prices
road.cc