There are probably a few ways to go on this issue, only you will know what is best for your situation. You will get lots of input, weigh it out for your situation and go where it feels comfortable. I'm not recommending this lens for you, but was looking at it myself as a possible low cost venture into a big zoom, in this case it is a 50-500 Sigma, an older lens. It is on Ebay....it will give you an idea of what may be available...I think it is an OS version as well. 500mm may be less than you are looking for. https://www.ebay.com/itm/SIGMA-DG-50-500-F-4-5-6-3-APO-LENS-NIKON-MOUNT-USED-IN-GOOD-CONDITION/202773262332?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

I think it is at a little over $227.00 at this point. I have nothing to do with the shop that is selling it, no stake.

At any rate, good luck in your venture.

I agree to disagree, I do not see the harm in trying the 1.3X internal crop, especially if you do not have the lenses and are considering spending your hard earned dollars on something like a TC. The 1.3X is a simple way to see what the extra MM might yield, for someone who does not have a case full of lenses. Since I have used both crop methods, sometimes in the same image, and am satisfied with the result, I will continue to utilize the additional tool Nikon gave me (and Sony gave me) when the need arises. It simply works for me. YMMV.

For the op - Save the money up for the better lenses. If someone cannot afford to buy a lot of gear based on a hunch, suggestions, or the simple wish for better closeups, they might want to try some options, especially those that don't cost $$.

I do not know the OP's Post Processing skills, but will say this; I do crop both ways, and both have their uses. The 1.3x allow me to fill the frame in a pinch, on the front end (if i don't have a longer lens with me) It doesn't cost any light or shutter speed, and also cuts vignetting with some lenses, and is quite useful on mirror lenses. I do mostly run and gun images... If I have the time for more serious setup, tripod, shutter release, etc., then the PP crop could suffice, but both work, and I often do not have time to stop and set up, I'm following a critter, or walking through underbrush, shooting one handed and holding onto something with the other, etc.

If the 1.3x crop allows me to frame and focus even more sharply on a distant subject, then anything I do in post will add to the result, I see no harm, no downside...a crop is crop, however performed. I suggested the idea to the OP not to start any argument, just to give an alternative to the torture of trying out different TC's and spending money, and maybe never using said TC's again (I have I think, 6 of them), and I have hardly ever used them again after trying, they should go to Ebay, but then some other poor soul will spend hard earned dollars and maybe not be happy. I have some Kenko's, they are OK, but they are not as good as the crop, either crop......