Check out the freeware WebODM. Donate $50 and they send you a program to easily install it. You must have a relatively new computer with minimum 16 GB of RAM. After that, it's all free. You can also use it with GCP's. I use it to calculate the volume of stockpiles of sand and rock that are about 35,000 C.Y. without GCP's. This program really works well, it outputs an orthophoto of the whole site which is scalable for using as a plan, with the perspective of straight down at every point. It also outputs a .LAZ file of point cloud data which I use in AGTEK Gradework 4D to calculate volumes of stockpiles. However garbage in - garbage out! You must fly the site using several patterns at differing heights and gimbal angles. I use DJI's GSP app to fly my
P4Pv2 for free.
I am starting to work with Ground Control Points. If you have an existing Topographic elevation plan, set your GCP's out where you know the elevations from the plan, or use landmarks in the plan such as storm drains and manholes, or top of curb elevations. If you don't have an existing topo to start from, then you need very expensive GPS equipment, requiring a monthly license fee to start your topo.
I started out using maps made easy. That site is good, and you can use about 70 pictures of 20 MP quality for free data output of a orthophoto and .las files. The problem being larger sites, and higher accuracy demand many more photos. On a 6 acre site I use about 300 photos at 20MP ea pic. using WebODM and it takes about 2-3 hours of processing time. I think that maps made easy is the least expensive because you pay per use, but they only have a Beta program for GCP's.
If your company will pay for Drone Deploy or other web apps, it will cost them about $300/mo PLUS another $50 for a map using GCP's!
I would recommend that you start with maps made easy for free, to get a feel for it. Then download and install Web ODM. It is surprisingly easy to use with great results, for free. Attached, find two orthophoto sites in San Francisco using WebODM. This Adobe Acrobat file is much smaller than the typical orthophoto tiff file for your easy download.