VMware Aria Operations 8.12 HF1
First, download the patch itself.
Once complete, it'll indicate as much.
Go to Environments, select your environment, the Operations tab, the three dots, Patches, and Install Patch.
You'll then be prompted for confirmation.
Click INSTALL and watch the progress.
Back in your environment, you can check Patch History to confirm it was installed.
You can always apply HF1 via the Admin UI of Aria Operation as well, details here!