Yep, create a Smart Campaign which contains a Fills in Form trigger in the Smart List. Then in the Flow, simply place a Change Score step, which adds a value of your choice to that lead's score. Then activate the campaign, and any future leads who fill out the form you specified will receive the score you set.
Note: If you want to add to the current score, make sure to include the plus-sign e.g. +50.
Give it a go and let us know if that does the job for you 🙂