How can we convert a 110 15 amp outlet to a 110 20 amp outlet. Can we just attach the faceplate for the 110 20 amp outlet. We are installing a hot sauna. Thank you.

Does this sauna require a dedicated circuit? If it requires a 20A receptacle I am sure it will be a HEAVY draw.

You can replace the receptacle with a 20A version IF it is wired with #12 wire and is on a 20A breaker. Be careful doing this for the reason mentioned above.