I don't see how it'd be a problem. Just makes it more of a stoop than a step.

I suggest:

I was coming here to say exactly what Mark said without a pretty drawing.

2.5 feet is not too much. It gives a landing space before entering the house. It could be even wider.

I suggest that if possible make that step as low as possible. I had our path slanted slightly so that the step up is 4inches. This makes it easier for the less nimble and also for rolators or other assistive devices.

Steps should be designed based upon a comfortable human stride as the steps are ascended or descended. The size of the tread and riser should allow someone to travel the steps without a stutter in their stride or have to take half steps or stretch their step to negotiate stairs.

There is a formula that can be used to determine the treat/riser ratio, but I have not used it in years. There is also a graph in the seventh edition of the Architectural Graphic Standards where the proper size tread and riser can be determined.

It looks like this step would lead up to a covered porch, which then leads to your front door. Given the amount of walkway room you have, if possible, I would not do a step at all. Instead, make it a gradual ramp up to the floor elevation of your covered porch. This reduces the risk of someone tripping. If you can regrade this so you have a walkway that gradually leads up to the porch, you can still have your planters on either side of the entry.

Thank you all for great advice!