Use a carport as a patio cover?

Roof pitch min. 2%
There is no place in DE without static snow load. There are reference values for each region.
Wind load should not be underestimated either.
With 6 posts 9*9cm, snow and wind should not be a problem.

Don’t forget the anchoring in the ground.

I would, for example, rather fasten one side to the house; that saves at least 3 posts and foundations with anchors.

My DIY carport cost me a total of 500 euros all in. The work with the hardware store model is the same.

However, I carefully reworked and sanded all the wood and coated it three times. It’s supposed to have a visible quality. ;)

Oh man, I think I need to go to the dealer and take a look at some carports and get advice on site.

Honestly: of course it's possible. But in the same price range there are also nice terrace roofs that look a bit more delicate. The main difference probably lies in the size: a carport with 3 x 5 or 2.5 x 5.5 might not really replace a terrace roof of 3 x 4. Added to that is the building permit, which you might need if one side is wider than 4 meters. The wood of carports is probably also a bit rougher, which some might like less.

Twin-wall sheets and flat roofs are not a good idea. Dirt really settles nicely there. That spoils the pleasure over time.

The wood of carports is probably also somewhat rougher, which might make it less appealing.

The wood is also not laminated wood, which is straighter and remains so. I have also seen cheap carports at the hardware store, where the rafters were just boards. Insufficiently wide as a support for twin-wall sheets.

I don't really like double wall sheets that much. Surely there are some decent solutions, but in my environment I have seen several solutions with them, and sometimes the sheets became cloudy, came loose, or absorbed water, which eventually looked dirty. The neighbor's garden house had a sheet occasionally flying around when it was very windy. That's just my feeling about it; I would rather choose glass. Earlier, wired glass was often used as well, which should also be an option. If you have a carpenter, etc., on hand, you can also have the suitable wooden beams prepared as a kit at the timber trade. If you make a slight slope away from the house, the water can simply run onto the lawn depending on the exterior setup, or you treat yourself to a simple gutter or bent sheet metal as a drain. The roof on the terrace or carport doesn't care whether you drink coffee underneath or park your car. If you use thinner wood, you need more supports, and you will see them too. Thin sheets often require more support points; otherwise, they will bend... you always have this play with dimensions and load-bearing capacities, and you probably also want to achieve a certain look.

Occasionally, a panel from his garden house would fly around the neighborhood when it was very windy.

Thin corrugated sheets need more frequent support, otherwise they will bend...... you always have this issue with dimensions and load capacities; you might also want to achieve a certain look.

The panels recommended in post 10 do not need additional support at 3 m width. 16 mm is the minimum anyway for roof terraces. The example you described for greenhouses is not representative, much thinner panels are used there.

Of course, the panels must be installed correctly. There are online construction guides. However, I am not allowed to link them here.

Holzhandel-Deutschland has a PDF.

Please remember condensation water / sweat water when using light panels. We had this problem with corrugated light panels. Under the roof batten, it was always wet in the morning and water dripped from every roof batten onto the terrace.
You should know this...... in winter, condensation water can occur on the terrace table or drops can be seen!
But where does the moisture come from??? The keyword is: condensation water!
In winter, the temperature of the light panels drops below freezing point. The moisture in the surrounding air settles on the underside and top side of the light panels and freezes there into ice. This usually happens at night, as temperatures often drop significantly then.
The next day, the sun shines on the surface of the light panels and warms them up. The previously frozen moisture under the light panel thaws and forms drops. If the drop is large enough, the only logical thing happens: it falls! And that directly onto your terrace table.
Is this normal? Yes, this is (unfortunately) normal.
But how can this process be prevented?
There is no completely correct answer here. What definitely cannot be prevented is the freezing of moisture on the surface of the light panel. So the only option left is to relieve the symptoms, i.e. to channel or catch the drops.
We now have a new terrace roof with twin-wall sheets and everything is dry.
To channel off the condensation water, it helps to increase the roof angle. The water droplet then runs down the panel and ideally drips off at the eaves.
Another possibility is to "catch" the drops. For this purpose, for example, a sun sail can be stretched under the light panels. These can also serve as shade providers in summer.
But beware! – Such a system can become a real problem for the light panels.
If such a fabric is mounted too closely under the light panels, heat, i.e. air warmed by the sun, can accumulate under the roof. If a critical temperature is exceeded, the light panels suffer irreparable damage.