Inflation is a property of a single currency. It occurs as a response of the currency users, when the currency fails to accurately track the value that the currency is supposed to be tracking. Particular free currencies may indeed be inflationary if their rules of issuance don’t work well.
So, some free currencies may indeed be inflationary. But fundamentally, free currencies as a whole will solve the problem of inflation by virtue of creating a competitive space for currencies. If people have free choice to choose the currencies they want, they will choose the ones that actually do help build wealth for them, which will be the ones that don’t have inflationary tendencies built into them unlike conventional money.