is there a way to trim and extend grid easily?

[architecwang]

It is so frustrated to teach aging engineers to drag that tiny circle to connect to the other grid line. and grid line is So so rudimental and important for every building. I've had enough of this. 

[ahjorn]

You may try using scope boxes with dedicated names. It may just be the tool you need.

[architecwang]

called it is a compromised way... LOL. it is hard to use as well...

[ToanDN]

2d or 3d extent?  They align automatically unless your aging engineers deliberately unlock them.  

[architecwang]

not that simple dude, not all the grids can be regular, and in a large project, there are a massive number of grids, it's exhausted to edit.

and no kidding, Axis is the fundamental element, those experienced (aging) people are always the decision-maker. The way of editing the grid in Revit, truth be told, is not smart.