Preset missing in Photshop 2021

[fdormoy]

I saw some Photoshop tutorials shwong a lartge amount of presets available with Photoshop 2021 but are now listed in mt preset menu or gradiant preset menu.  I understand that I need to download them in Photoshop but cant find the way.

In the first picture I attach, it shows my screen with very limited present.

In the second picture it shows a youtube tutorial showing many more gradient preset that I currently do not haver access.

The thrid picture shows my Adobe Photoshop 2021 directory where. for example, sky-presets directory is empty.  

I would like to show in these menus all presets made available from Photoshop which are not automaticaly incorprated in the software.  Can someone help me doing this ?