How to customize x axis tick labels for ggplot2 object created by plot() method

Question

I use ggeffects::ggemmeans() to get predictions for a model. The output of ggemmeans() is of class "ggeffects", and there's a plot() method for quickly visualizing the prediction. Although the resulted visualization is a ggplot object, I can't customize the labels of the x axis ticks.

Example

library(emmeans)
library(ggeffects)
#> Warning: package 'ggeffects' was built under R version 4.0.4
library(ggplot2)

my_model <- lm(mpg ~ factor(am), mtcars)
my_ggemmeans <- ggemmeans(my_model, terms = "am")
p <- plot(my_ggemmeans)

p

^{Created on 2021-04-28 by the reprex package (v0.3.0)}

Problem

I want to edit the labels of x axis ticks to replace 1 and 0 with "manual" and "automatic"
Although p is a ggplot object:

> is.ggplot(p)
[1] TRUE

I can't use scale_x_discrete(). For example:

p +
  scale_x_discrete(labels = c("manual", "automatic"))

Returns the following warning:

Scale for 'x' is already present. Adding another scale for 'x', which will replace the existing scale.

and the undesired plot:

What happened to the x axis tick labels?

Bottom line: how can I operate on p to replace the x axis tick labels?

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EDIT

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@Ronak's answer below suggests to rely on scale_x_continuous() and supply both breaks and labels arguments. However, this solution lacks "specificity". We can't pass a named vector to labels argument in scale_x_continuous() the way we can with scale_x_discrete() (see reference). This means that the code

p + scale_x_continuous(breaks = c(0, 1), labels = c(`1` = "number one", `0` = "number zero"))

Gives mismatched labels:

Answer 1

Use scale_x_continuous :

p + scale_x_continuous(breaks = c(0, 1), labels = c("manual", "automatic"))

It still gives the message that it is replacing the previous scale with the new one.