How can i give options to improve performance on a client?

I have some questions about it:

1 If you have some parts/meshes and you make them complitely transparent are they still get render from the client? For example if i want to give options in a client to be able to have like High/Medium/Low level of quality how can i do that but without calling Destroy on these parts/meshes as you can’t change between these options as they will get deleted from the client?

2 I have some unanchored stuff and physics are very expensive. If i give the option for a client to be able to anchor them these it will improve performance right? And basically the server will not make network owner that player anymore for these parts?