Well you also need to be eating at a calorie surplus of a few hundred extra calories per day, but that will ideally happen naturally if you focus on adding more protein to your existing diet. If you’re going the protein powder route, you’ll probably want to have it as an extra meal rather than a meal substitute. If you still struggle, you may need to track your calories to help you adapt.
YouTube can be a good source for some high protein vegan meal ideas. If you can do soy, TVP is a good option. If you can do gluten, chickmeat/seitan is good.