How to make this?

[TIG]

EEbyOffset will accommodate non-right-angle corners BUT all edges must be coplanar for it to work...

A relatively easy way is using the native Offset tool on each face [double-click to repeat last use offset dim], with some subsequent Move tool use on edges/vertices IF the offset isn't needed to be 'all round'...

[cupko]

I should emphases that geometry is complex. I am practicing making a car from blueprint and there's a lot of triangles.
Easiest way to do this would be to select edges and then chamfer. This is not the only place where I need to do this .

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[bjornkn]

Take a look at Tools On Surface and Joint Push Pull (JPP)

[cupko]

I've made this with those tools, but it's slow and unprecise.