How to represent the effect of one covariate on regression results?

My question is how do I present/plot the effect of covariate "TD" in
the example it has "P" equal to 3.32228e-12 for all IDs in the
resulting file so that I show how much effect covariate "TD" has on
the analysis. Should I run another regression without covariate "TD"

I'll take a second shot in the dark:

There is R^2, and a number of generalizations.
(The most common of which, is probably adjusted R^2).
And there are various other goodness of fit tests.

https://en.wikipedia.org/wiki/Goodness_of_fit
https://en.wikipedia.org/wiki/Coefficient_of_determination

You could fit two models (one with a particular variable included, and
one without), and compare how the statistic changes.

However, I'm probably going to get told off, for going off-topic.
So, unless any further questions are specific to R programming, I
don't think I'm going to contribute further.

Also, I'd recommend you read some notes on statistical modelling, or
consult an expert, or both.
And I suspect there are additional considerations modelling genetic data.