Should I learn flexbox or grid first (I am a beginner)

Answer 1

First you try to position elements using margin padding float (postion+left+top)
(Means basic)
After that go to flexbix and grid.

Answer 2

Of course you don't need to learn them first it's recommended to learn basics , you need to know display property and how to modify it so that getting the suitable display for your website
Learn it gradually
1- Display, float
2- position (absolute, fixed, sticky,relative...)
3- training well on them by coding creative navbars
4- learn css grid
5- apply what you have already learn step by step in your projects
6- learn flexbox and applying them as well
It's also important to note that any professional website used these properties so take your time in training on them well