The radius of other stars can be deduced indirectly from their luminosities and temperatures.
Stars have a wide range of radii.
Very few stars have had their angular size measured. Most stars are so far away from the Sun that their angular size is not resolved, even in large telescopes. They appear as points of light. Only one star other than the Sun has been seen as a disk, rather than a point. The Hubble Space Telescope made a direct image of the star Betelgeuse.