Can anyone tell me what this sort of expandable toolbar, containing sliders, is called? I'm still a beginner in development and can't seem to find this views name, or any place where to learn it.
Thanks

Can anyone tell me what this sort of expandable toolbar, containing sliders, is called? I'm still a beginner in development and can't seem to find this views name, or any place where to learn it.
Thanks
It is a modal/half sheet/popover not available in SwiftUI as a pre-built View
.
You can add the sliders, tab view and segmented picker per your requirements to the modal.
There are many way to implement it.
in iOS 15 Apple has provided adaptiveSheetPresentationController
so it can be implemented using UIKit.
Here is a WWDC21 video too
There are other ways, the referenced question has many solutions.
As @loren Epsom said, its a half sheet, and as its not pre built view in SwiftUI, I recommend using this framework, if the nature of your work allow 3rd party frameworks, Partial Sheet
The setup is pretty straight forward, for example you can use something like:
.partialSheet(isPresented: $isSheetShown) {
//Add the SwiftUI view that you want to appear in the partial sheet.
}
Read the How to Use