Fill inn gaps in data of multiple regression model


So I have some data consisting of only 3 datapoints.

What I want to do is fill in every x value with the corresponding Y value from the graph in the dataset. What is the easiest way to do this?

I think you actually mean to interpolate between values, there are many ways of doing this. I let you some examples in the link below.

If you need more specific help, please provide a proper REPRoducible EXample (reprex) illustrating your issue.