Similiar to an on-premises vSphere deployment, VMware Cloud on AWS follows good security practices by isolating and preventing access to the SDDC Management Network including Virtual Machines running in the Compute Network. With that said, the SDDC can be configured to enable access to the SDDC Management Network for either all or subset of workloads running in the Compute Network.
I have seen this request come up a few times, usually around proof of concepts, lack of on-premises infrastructure or wanting to run completely isolated within VMC for Dev/Test purposes. Below are the step by step instruction on setting this up for both an NSX-V and NSX-T based SDDC. Once enabled, customers can access the vCenter vSphere UI from within the specified Virtual Machine(s) including using tools like OVFTool or PowerCLI for importing new or existing workloads.
Note: Please refer to this blog post here to determine if you are running an NSX-V or NSX-T based SDDC.