Create and save preset nodes in the 2.81 blender, for example for material and texture I would like to ask you how you can save settings related for example to texture materials and various procedures carried out with nodes in the shading editor in order to always find them ready for the occasion, in case you want to use a certain effect created in the past
So you mean, you need a technique which can help you make a library of your node setups so you just have to click to import.

There are some free/paid addons out here to do this action. 

https://blendermarket.com/products/node-kit (paid) 
https://blendermarket.com/products/nodecustombuilder  (FREE available but can also be purchased to donate to the developer) 

If you want to achieve this natively in blender without any addons, 
Just save your favorite node setups in your dedicated node group blend file.

Whenever you need that node setup or material, 
You can go to file > append > your dedicated blend file and apeend node group or material you like