The greatest changes that have taken place in many respects over the past few years, are of course the internet, the mobile phone and the various private messaging services such as whatsapp that proliferate with new services being announced almost daily.
Whilst in practice as a solicitor in England I well recall the days when to look up a relatively obscure legal point or decision one had to visit the Solicitors' Law Society Library. Securing the information could take about a week only to find that it might not be fully on the point thus necessitating a supplemental search. Today however the information and supplemental information can usually be traced in seconds through say Google.
The importance of the above to daily lives in C21 (they hardly existed in most of C20) is clear. However today looking at movies or TV programmes that concern the pre-internet/mobile era is often more enjoyable than those which rely on all of C21's modern gadgets for their plots.
The Chinese sadly now appear to restrict their population's access to many internet sites when views or opinions or even news shown on the sites, are not to their government's taste; the Iranians sometimes seem to imprison people for what seem to me to be similar reasons although as the Australian and Iranian recent prisoner swap may signify, the motivation of the Iranians may be rather different from that of the Chinese.
The Chinese however have pushed forward very speedily with their development of 5G technology through their Huawei brand, which the US government is banning and is keen for other countries to do likewise, on the grounds that it contains hidden spyware which would harm nations' defences. Whether the UK follows the US lead as regards Huawei is unclear as yet, as are the questions of what spying there might be and what actual harm it might be capable of.
I doubt that 5G which BT is apparently developing and introducing into the UK market will be of much personal interest however.