A few important lessons here.

You dont tell someone NO. You say, I could do this, or I could make this change and it would work in a standard way. If you want me to do it this other way, I can but it is going to cost XXX extra hours to build it, and probably incur a lot of future work to maintain our own "version" of this.

Then when they say "do it that way" you go into your planing meetings and say "task xxx is 2x longer for a design deviation"

Make sure if you say this, it goes in an email. You know why all the old people send you emails for bullshit? Because we have all been burned and know that we can keep copies of that for CYA reasons.

I didn't see an email (a lot of them) is a bad excuse 6 months down the road. When the bills come due and the design team is getting a beat down.