Not always. All image frames taken with a camera naturally include the bias. If you subtract a dark from the light frame, and subtract a flat-dark (one that matches the exposure duration of the flat) from the flat-field, then bias is already subtracted from both. You do not need a separate bias frame.
Bias frames are required if:
You are using exposure scaling for the dark frames, or
You are using flat-field frames and do not have dark frames with the same exposure duration as the flat-field frames (”flat-darks”).
Bias frames work well with CCD cameras, but often do not work properly on many CMOS-based cameras. If you are using a CMOS camera that utlizes HDR functions, in-camera stacking modes such as StackPro, or changes operating modes at different exposure times, the bias frames generally will not match the light frames. It is a good idea to verify for yourself that exposure scaling works properly.
The best method is to use "light-darks" and "flat-darks"; that is, dark frames that match your light frames, and dark frames that match your flat-field frames. Very short flat exposures will not have much dark current, and as such it may be sufficient to subtract a bias frame, or a dark frame matching the shortest flat exposure.
Another strong recommendation is that you average the noise out of your calibration frames of all types. You should capture at least 10 frames of each type. The calibration tools in MaxIm DL will combine them automatically.
If you are not doing photometry (brightness measurement), and the image is sufficiently clean for your purposes, then you do not absolutely need a flat-field frame. Nor is a flat-field absolutely necessary for astrometry since the centroid algorithm used is quite robust; however it may help if the signal-to-noise ratio is poor. For general imaging, there are alternative methods to correct overall vignetting, such as the Flatten Background command. A can of compressed air is very effective for dust donuts. Nevertheless, if you want the best performance from your camera, or are doing photometric measurements, then a flat-field frame is mandatory.
As an absolute minimum, you should always subtract at least a dark frame. The Camera Control Panel includes an auto-dark feature that should be turned on if you are not otherwise calibrating your images. It is however always better to average dark frames if at all possible.