##Eberron Shifter is your best bet##
The Wayfinder's Guide to Eberron has a new race, Shifters. Their "Similar and Diverse" description gives great flexibility to their appearance:
Shifters are similar to humans in height and build but are more naturally lithe and flexible. Their facial features have a bestial cast, with large eyes, flat noses, and pointed ears; most shifters also have prominent canine teeth. They grow fur-like hair on nearly every part of their bodies.
The traits of the beast within affect a shifter’s appearance as well. [...] While a shifter’s appearance might remind an onlooker of an animal, they remain clearly identifiable as shifters even when at their most feral.
In particular, the Longtooth subrace:
Longtooth shifters are fierce and aggressive, but they form deep bonds with their friends. Many longtooth shifters have canine traits that become more pronounced as they shift, but they might instead draw on tigers, hyenas, or other predators.
or the Wildhunt subrace:
Wildhunt shifters are sharp and insightful. Some are constantly alert, ever wary for possible threats. Others focus on their intuition, searching within. Wildhunt shifters are excellent hunters, and they also tend to become the spiritual leaders of shifter communities.
would likely be most appropriate for someone wishing to play a fox (or a fox like) race.
Alternatively, the Simic Hybrid could also work
The Simic Hybrid race from the Guildmasters' Guide to Ravnica could also work quite well, but you would need to work with your DM to find more appropriate Animal Enhancements than the version presented in the book.
For reference, the description of the race has the following relevant text:
In recent years, the Simic Combine has extended this research to humanoid subjects, magically transferring the traits of various animals into humans, elves, and vedalken.
[...]
A hybrid’s biological enhancements can change its appearance drastically, though most hybrids retain their basic physical form. All are augmented with characteristics of animals, mostly aquatic, reptilian, or amphibian creatures. These include crab claws, squid tentacles, wings or fins like those of manta rays, translucent or camouflaged skin, or shark-like maws filled with sharp teeth.
