For SOME unusual conditions, generally, as Grumpy says, convergence issues (eyes don’t work together) or possibly some forms of strabismus (misaligned eyes), both issues related to the actual muscles, you can get some improvement, generally eye exercises to improve vision don’t work. This is because most vision problems; myopia (near sighted), hyperopia (far sighted) or astigmatism are the result of a misshapen eyeball, and no amount of exercise can correct that.
There are many exercise programs out there. The most well known is the Bates method. While there is much anecdotal testimony that this works, in controlled clinical studies, zero improvement was shown. Many patients where I work have tried it over he years (there is a clinic in a nearby town), and they all still wear glasses.