Architectural planning costs 50% more expensive than agreed.

. I think the best option is to buy a house or an apartment that an architect has built for themselves.

I don't believe that, because everyone has different needs when it comes to living. A house or an apartment must suit the resident. But that does not mean it will suit the next resident just as well. One person needs a home office, another wants to accommodate their grand piano, the third lives alone.

the question is only: who already has such a delta between original expectations and result with the first planning contract (to the architect) ... ... how well does that person have the contractors of the individual trades under control?

not at all, see:

a few days ago he asked us to submit our planning to the general contractor with a request for a cost proposal.

I read that as 2. no tender by him, but price inquiries by the builders (probably only with plans, without a description of the construction services) and 1. as a modestly veiled question of when he may finally send his final invoice but definitely not as an indication of impatient desire to finally prove himself on the construction site. In my opinion, he could not do that either. Forum community : did the OP go overboard?

Hello, sorry, I didn’t mean to be rude and not respond to all your answers. My son was sick, I was sick... everyone was sick.
Anyway. Everything looks like a reason to run away. So far, we haven’t found a single [GU] who would even provide a quote for our project. Next week we have another meeting with a [GU]. That is where my hope lies.
Our architect recently wrote an email saying he is going on vacation for a few days and is coming up with a battle plan. We are curious.

Managing individual contracts ourselves is unfortunately not an option for us. We have neither the time nor the slightest clue. In case of doubt, only a prefabricated house remains, and taking the architect’s fee as a learning expense.
But both the pandemic and the Ukraine war make everything immensely difficult.

Hello, sorry, I intended to be rude and not respond to all your replies. My son was sick, I was sick... everyone was sick.
Anyway. It all looks like a reason to run away. So far, we haven't found a single general contractor who would even estimate our project. Next week we have another meeting with a general contractor. That's where my hope lies.
Our architect recently wrote an email saying that he is going on vacation for a few days and will come up with a battle plan. We are curious.

A single contract award, which we coordinate ourselves, is unfortunately not an option for us. We have neither the time nor the faintest idea. In case of doubt, only a prefabricated house and see the architect’s fee as a learning cost remains.
But both the pandemic and the Ukraine war make everything extremely difficult.

I already wrote it at the very beginning. There are indeed prefabricated house providers who are happy to implement your architect’s plans. You can still change things in the construction planning (e.g. to save costs). I would definitely try it before throwing money away...

Our architect recently sent an email saying that he is going on vacation for a few days and is coming up with a battle plan. We are curious.

Not me, my crystal ball sees a battle plan in three parts for his vacation: 1. applaud the pilot upon landing, 2. all you can eat, 3. shopping for souvenirs. That won’t help you :-(

I already wrote this at the very beginning. There are indeed prefab house suppliers who are happy to implement your architect’s plans.

No matter whether stone or wood general contractor: if you show up with plans for a house planned 40% too large and 50% too expensive, they won’t magically be able to rightsize them. Instead, you will have the choice to have them build a house according to the plans (and then too expensive) or according to the budget (then nothing will remain of the plans except symbolic details). With plans deviating to that degree, I only see the two aforementioned ways or as a “third” a compromise between these, but not much else that can be done.

My plan would therefore remain to have a lawyer knowledgeable in architectural law assess the situation, slaughter the architect’s dreams of getting paid for the nonsense, and try to obtain reasonable compensation for the wasted time.

No matter whether it's a stone or wood general contractor: if you come to them with plans for a house that is 40% too large and 50% too expensive, they won't magically rightsize it (or be able to). Instead, you will have the choice to have them build a house according to the plans (and then it will be too expensive) or according to the budget (in which case nothing but symbolic details will remain of the plans). With plans that deviate so much from the target, I only see the two aforementioned options or as a "third" option a compromise between them, but not much else to do.

My plan would therefore be to have a lawyer knowledgeable in architectural law explore the matter, "slaughter" the architect's dreams of payment for nonsense, and try to get a reasonable compensation for the wasted time.

I was referring to this statement:

So far, we haven't found a single general contractor who would even calculate our order.