Under What to expect on this support page, it says:
The phone branding, network configuration, carrier features, and system apps will be different based on the SIM card you insert or the carrier linked to the eSIM.
The new carrier’s settings menus will be applied.
The previous carrier’s apps will be disabled.
The correct approach from a UX perspective would have been to display an out-of-box experience wizard that gives the user an option to either use the recommended defaults, or customize what gets installed.
Unfortunately, many manufacturers don’t do that, and just install the apps unconditionally and with system-level permissions. And even if they did, it’s likely that many of the carrier apps will either have a manifest value that requires them to be installed, be unlabeled (e.g. com.example.carrier.msm.mdm.MDM), or misleadingly named to appear essential (e.g. “Mobile Services Manager”).