Use CreateMultiRegionAccessPoint with an Amazon SDK or CLI

Configure the S3 control client to send request to the us-west-2 Region.

        suspend fun createS3ControlClient(): S3ControlClient {
            // Configure your S3ControlClient to send requests to US West (Oregon).
            val s3Control = S3ControlClient.fromEnvironment {
                region = "us-west-2"
            }
            return s3Control
        }

Create the Multi-Region Access Point.

    suspend fun createMrap(s3Control: S3ControlClient, accountIdParam: String, bucketName1: String, bucketName2: String, mrapName: String): String {
        println("Creating MRAP ...")
        val createMrapResponse: CreateMultiRegionAccessPointResponse = s3Control.createMultiRegionAccessPoint {
            accountId = accountIdParam
            clientToken = UUID.randomUUID().toString()
            details {
                name = mrapName

                regions = listOf(
                    Region {
                        bucket = bucketName1
                    },
                    Region {
                        bucket = bucketName2
                    }
                )
            }
        }
        val requestToken: String? = createMrapResponse.requestTokenArn

        // Use the request token to check for the status of the CreateMultiRegionAccessPoint operation.
        if (requestToken != null) {
            waitForSucceededStatus(s3Control, requestToken, accountIdParam)
            println("MRAP created")
        }

        val getMrapResponse = s3Control.getMultiRegionAccessPoint(
            input = GetMultiRegionAccessPointRequest {
                accountId = accountIdParam
                name = mrapName
            }
        )
        val mrapAlias = getMrapResponse.accessPoint?.alias
        return "arn:aws:s3::$accountIdParam:accesspoint/$mrapAlias"
    }

Wait for the Multi-Region Access Point to become available.

        suspend fun waitForSucceededStatus(s3Control: S3ControlClient, requestToken: String, accountIdParam: String, timeBetweenChecks: Duration = 1.minutes) {
            var describeResponse: DescribeMultiRegionAccessPointOperationResponse
            describeResponse = s3Control.describeMultiRegionAccessPointOperation(
                input = DescribeMultiRegionAccessPointOperationRequest {
                    accountId = accountIdParam
                    requestTokenArn = requestToken
                }
            )

            var status: String? = describeResponse.asyncOperation?.requestStatus
            while (status != "SUCCEEDED") {
                delay(timeBetweenChecks)
                describeResponse = s3Control.describeMultiRegionAccessPointOperation(
                    input = DescribeMultiRegionAccessPointOperationRequest {
                        accountId = accountIdParam
                        requestTokenArn = requestToken
                    }
                )
                status = describeResponse.asyncOperation?.requestStatus
                println(status)
            }
        }