Customize AE project without going inside of it - like Nexrender

Hi all,
Does anyone know how customize after effects project assets and some parameters without going inside after effects? I Tried nexrender but it doesn’t have many options. Pls let me know.

Thanks

What parameters need to be changed?

I wanna change mainly duration, do you know how?

If it was something that can be controlled with expressions I’d have said you can try to link it to a spreadsheet, but as duration is not controllable I don’t have a straightforward solution. I don’t know nexrender.

ok thanks man