First off, kick your architect in the nuts for not having dealt with this in the specification. I bet they’ve designed stupid shaped windows and everything haven’t they?
Edit I see self designed.
Temporary is OK but, bear in mind any real option for these is going to be big and structural. Ideally it should be a designed in solution not something to do after the house is finished.
The correct answer to your question is something like louvolite perfect fit or eclipse (closed at the moment) intu systems. They’re not expensive, will work and not look utterly crap and want binning in 6 weeks time.
Do NOT use film as a temporary.
Nothing external is going to be anything more than very very temporary or permanent.
Long term properly done…
External solutions work well, much better than internal for heat control.
Film is OK but not great for heat reduction, even the best films don’t have a great shgc compared with a half decent fabric and a decent fabric is much more effective outside than in.
7m is a big chunk of glass for a single system unless you go for some sort of awning/pergola etc.
If you’ve space a pergola would be my suggestion as it makes the outdoor space more usable and you’ll be less bothered about direction of draw. Brise solais is a better solution if you’re commonly getting high winds and sun at the same time as fabric systems will need to retract on much lower winds.
If you’ve not got space…
I’m guessing your bifolds open outwards, so anything you do externally will need to clear that (those crazy euros have them open inwards because they like external systems, outwards opening in the UK because we like things that don’t work very well.)
Regardless of internal or external rollers or venetian will work well but need splitting to suit 7m, practically I’d guess into three. Fabric/louvre material choice is key, “pretty” things are generally crap in terms of performance. Technical stuff that does a good job by and large doesn’t come in pretty options, that’s not to say they’re unattractive but they’re not floral patterns and the like either.