You can't have a position hold without GPS and magnetometer. GPS tells that it drifted, and magnetometer is needed for heading, so it knows in which direction to correct for the drift (GPS don't tell where nose is pointing). Both sensors are needed and mag must be placed far from magnetic interference which on small racer might be difficult, but not impossible. Also properly working altitude hold is needed which uses barometer.
Please have a look at this post
https://forum.librepilot.org/index.php?topic=15.msg36#msg36Using just gyro&accel sensors alone (typical for racers), quad will inevitably drift a bit, but NOT that much (if calibrated/build properly) that it makes any problem and if there is no strong wind.
The
Eachine Racer 250 on Banggood has Control Copter 3D (CC3D) compatible/clone board, not a Revolution board. Only Revolution (or more advance autopilot boards) have enough RAM and sensors to perform autonomous flight and position hold.