Alan S Tait did some illuminating work in this area, looking at IMF data, and found no major effect on inflation from the VAT of implementation. He observed that 33 out of 41 countries which had introduced VAT in the past 30 years had seen no material rise.
Of course, direct intervention in price rise supervision around the launch dates of VAT can suppress any inflationary effects. India’s recent switch to GST has come with heavy auditing of pricing rises, including shop-by-shop audits. This follows the historic success of Austria, France, Korea, Norway and the Netherlands.
In summary, there may be a one-off hike in the short term, but then drops out of the inflation measure the next year. Even this rise is usually mitigated or controlled by other government actions. So economists generally agree there is no meaningful inflationary impact to implementing VAT.