Adding more information to YutongTie-MSFT comment, yes there are other European regions which support VMs of type Standard_DC4ds_v3.
You can use below command to check VM-family vCPU quotas:
az vm list-skus --size Standard_DC4ds_v3 --output table
The output you will get as all regions which support type Standard_DC4ds_v3.
As you are looking for European regions, below are two regions that support VMs of type Standard_DC4ds_v3. I have verified in portal also, please select zone accordingly in which size is available.
Germany west central - zone2
Switzerland north - zone3
If you are not able to deploy it may be limitation for your subscription, you can increase quota family. For detailed information on how to Increase VM-family vCPU quotas, please look into https://learn.microsoft.com/en-us/azure/quotas/per-vm-quota-requests
If you have any further queries, please do let us know.
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