Custom model only on these region:
US East (N. Virginia)
US West (Oregon)
Europe (Frankfurt)
https://docs.aws.amazon.com/bedrock/latest/userguide/model-customization-import-model.html
Fine-tuning is supported in the following Regions (for more information about Regions supported in Amazon Bedrock see Amazon Bedrock endpoints and quotas):
US East (N. Virginia)
US West (Oregon)
https://docs.aws.amazon.com/bedrock/latest/userguide/custom-model-supported.html