It's a bit different with Apple because they have created their own iOS software exclusively for their iPhone's and iPads so they have 100% direct control over it.
Samsung don't make Android but instead add their own flavour to it and add Samsung One Ui when it becomes available to them.
Also Network's have no say or input whatsoever when it comes to iOS releases which is why all iPhone's are unbranded and have no delays in release caused by the Network's @abzyndbf
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 3.1/ Android 11.