Large glazed areas can be a challenge as you may wish to control the amount of light coming into the room during the summer months and reduce the big black hole syndrome during the winter. In large open plan kitchen /living areas there may also be a problem of resonance with noise bouncing off hard surfaces.
Curtains or heavier Voiles can all be considered when choosing window treatments for bi-fold doors.
Consider heading styles with tight efficient stacking as large windows mean large stacks. Tracks can be top fixed onto ceilings or within recessed pelmets or on made to measure pelmets in the same fabric as the curtains.
Heavier voiles are popular as they filter light in very sunny exposition, give privacy during day and night yet will not detract from the airy and light feel of bi fold doors. They can be unanchored and free flowing so can be positioned on the track according to need.
Roller blinds are a possibility if there is room at the top of the recess to stack the blinds. Usually roller blinds are automated as it is impossible to fit the chains and make them child safe. Beware of blinds becoming unbalanced if used when doors are open and there is a breeze. Roller blinds can also become scuffed and dirty at the base if they are dropped to the floor which is very noticeable when the blinds are raised.
If you have a smaller window in the same room as the bi fold doors consider using a roller blind laminated in the same fabric.