If what you're wanting is National Geographic-like wildlife pics, then be prepared for a huge case of sticker shock, thousands of dollars just for a lens, and the complete lack of any thing close to being convenient for travel. (See Roger Cicala's lensrentals video on the Canon great white supertelephoto lenses).

You could get the Canon EF 75-300 III, but this is a very limited lens, and you will end up gaining technique to use it well or end up with a lot of blurry photos. The 70-300 IS or 55-250 IS models would be better, but are going to be more expensive. But you could also consider renting a 100-400L superzoom for the trip. But that is a $2000+ lens you'd have to haul about and keep track of.

Also, I use the Canon EF 400mm/5.6L lens (600mm equivalent on my APS-C dSLR) to shoot birds and deer in the back canyons here in Southern California and it's often not long enough. Just so you have a sense. With wildlife, your field craft actually counts for more in terms of how close you can get.

Just me, but I'd say consider getting a superzoom bridge camera, like a Panasonic FZ-series model. This is a fixed-lens camera with supertelephot equivalency on the superzoom lens it has because it uses a much smaller sensor (1"-format or 1/2.3"-format) vs. a dSLR or mirrorless camera would. The image quality may not be as high, but it should still be higher than what you can get with a smartphone and accessory lenses.

You will want to check in reviews on how fast the cameras shoot and autofocus, though. Wildlife tends to move fast. Shutter lag can be very frustrating.