Oh jeez, first thing I'd do then is take a look at the PS4 exclusives (there are still a decent number), look at potentially signing up to PSN Plus as they potentially still give away the PS4 collection (~20 PS4 games); and also consider an external SSD for the PS4 games as you can eat up the built in SSD fairly quick. Honestly, Sony's upgrade policy is nothing like that of Microsofts; however virtually all games run as though the machine is a PS4 Pro or better; even if they don't have a PS5 upgrade patch, so if you've not had a PS4 at all, there are some great games for you to play there alone. Might as well start there also, as then upcoming PS5 games will be all the more technically impressive.
I've also picked up a lot of PS4 games in recent months; as the move towards PS5 means a lot of PS4 games are now getting relatively cheap. This is worth bearing in mind because SOME PS4 games essentially allow you to download an upgraded PS5 copy. You still need to put the disc in to validate you own it, but basically does mean you can buy the cheaper PS4 copy, and still play the enhanced PS5 game. This upgrade scheme is more present on disc versions of PS4 games than download so bear that in mind.
If you like Spiderman, then Miles Morales (get Ultimate Edition, it costs more but comes with a code for the Remaster of the previous Spiderman game which is a PS4/5 exclusive, and also a bigger, longer game than MM, so definately worth the extra £15 or so).