Technically it is possible. You don't need an equal or larger market cap to inflate something else 90%. You just need enough to dominate the trading volume.

As an extreme example, if bid/ask volume is exactly 1 (ie the ONLY trade volume consists of you and 1 other person trading a quantity of 1), then at the minimum, all you need is a bank roll of 1.9x the current unit price, with both you agreeing to the trade it for 1.9x, for the going price per unit to inflate 90%. And since market cap = price per unit × units outstanding, then the market cap also inflated 90%. If the units outstanding was 5000, and the unit price was $1, then the market cap increased $4,500 using only $1.90.

Look at trade volumes. Tether is massively bigger than bitcoin and ethereum combined.