I do real estate photography professionally. I'm sure it's a little different in every city, but if it's anything like where I live, the market is way over saturated by people trying to get into the business (including realtors themselves who are too cheap to pay $150 for some photos on a $1M+ property because it cuts into their $30K+ commission). It is not lucrative unless you are the owner of a full time operation, and is much more suited to a side gig. It's also very time consuming if you want to do a really good job, so the $/hr is pretty bad. Not a big deal if you're doing it for fun though.
If you want anyone to take you seriously, you will need a good, robust portfolio. That is the first thing they will ask to see if you approach someone offering services like that (especially if they already have someone they're happy with), and you had better either be as good or better as the competition (of which there is probably a lot of), or way cheaper. Remember that they probably get approached a lot by people who buy a DSLR or drone from Costco with zero experience thinking they can do professional work for professional money because they have professional equipment. An outstanding portfolio along with references is how you break through that initial barrier. Try to find some friends with really nice houses and start building a portfolio, or offer to work for free until you have built one up (and ask to use them as references if they are happy).
Another really important thing to consider is that most real estate photography companies do both the standard indoor/outdoor photography and the video/drone shots - realtors do not want to deal with and schedule two or more separate companies when they can just deal with one (and get a package deal as well), so if you are only offering video/aerial services and not traditional photography services, you are going to dramatically reduce your potential client base. Lots of realtors also want walk-through videos and virtual tours now, so maybe brush up on your indoor flying as well if that is not something you already do.
In my experience, finding one or more realtors and becoming their "go to guy" is the way to do it if you're just looking for side jobs. You also need to make yourself readily available, because they are busy too and if they have to fight you for scheduling because you work a 'day job', they are just going to use someone who is more reliable and does this full time. This can be especially difficult if you live somewhere that gets dark before a normal workday ends during certain times of year. I have found that contacting people with existing listings to offer services is met with offense 9/10 times, because the only reason you would be offering them your services is because you don't think their current listing is good enough, and chances are the agent took their own photos/video that you are offering to replace. It didn't matter how polite I was or how I worded it, they seemed to hate this and I learned the hard way. The realty business is extremely shady, and in my experience most realtors ignore their fiduciary duty to the client any time it benefits them financially.
Your biggest challenge will be entry barriers. Most realtors and/or agencies already will have photographers/videographers they work with, and there will need to be a heck of an incentive for them to switch, which will be difficult to provide if this is just a side gig for you and with pricing already so low for professional work. Your best bet will be to try and find one or two realtors (or any friends/family that are realtors) and link up with them so that they just call you whenever they have a new listing.
Pricing is different in every area. Just start Googling all the real estate photography companies in your area (most of them probably already offer aerial / video / virtual tour services) and that will give you a pricing indication. Be honest with yourself when determining a price, which should be determined by your experience and quality of the final product relative to your competition, and not as much by how long it takes you. Again, I think if you don't also offer traditional interior/exterior photography services you are going to have a much harder time.
Personally I would never deliver anything other than a fully edited/graded product unless specifically requested otherwise. Realtors want something with a short turnaround time that is ready to put directly into their listing.
