@Cheburashka is right that you can draw 16A from your 15A receptacles since they are wired to a 20A breaker (I am assuming that the electrician did it correctly and used 20A wire, and for a garage built in 2019, that’s a very safe bet).
You’d use something like this along with the Tesla 5-20 adapter.
But it is really easy to replace one of your garage receptacles with a 20A receptacle. Just flip off the breaker first. Btw, by code, the garage receptacles should be GFCI protected which could be by a GFCI breaker or by a GFCI receptacle.