I want to enlarge my front porch if the price is right

Probably need to call a contractor in your area. I find that is usually the best way to get a general estimate...many will come and do a free estimate in my area.

You need a contractor, each area of the country and each house is different. Get at least 3 written estimates from licensed contractors. Here is how to hire a contractor.

https://www.consumer.ftc.gov/articles/0242-hiring-contractor

It depends on what kind of materials you use. Are you using concrete, a composite, pressure treated lumber etc. Are you going to put up a railing? Again what materials would you use. Are you putting electric sockets or any type of lighting on the new porch? Are you going to want to cover it and how? You can do a removable awning or something more permanent. Then there's extra support needed for a permanent one. After deciding on those things, then it depends on where you live, because the cost will be different in different parts of the country.

You should first think about materials and exactly what you want now and if you plan on doing more in the furture, then contact some contractors. They will be happy to give you an estimate. Get several estimates and also make sure you are comfortable with the contractor you chose. Remember, the lowest estimate isn't always the best bargain. Make sure that all estimates include the same materials. Also ask who gets the permits.

Here are some points to consider before you get started on this diy project-https://www.doityourself.com/stry/how-to-expand-a-porch