When Requesting An Extension At Work messages in a Calm tone

I underestimated the time needed here—can we extend the deadline?

Let me know if this works or if you'd prefer another approach.

I should have flagged this sooner—can we extend the deadline?

Let me know if this timing works for you.

I can have a revised version by [new date].

I can have a strong version ready by [new date].

Quick heads-up—I may need a bit more time on this than expected.

I want to make sure this meets expectations.

Hi—I wanted to ask if I could have a bit more time on [task].

I want to make sure the quality is where it needs to be.