The following pre-processing methods were eliminated: 'center', 'scale'

[lic]

After downloading the caret package again and running it again, there was still an error. Could you please help me take a look? Thank you

[FJCC]

I can't be sure without seeing your data, but I suspect that all of the columns in df_train are characters and there are no numeric columns. Here is an example where the data originally works with preProcess() but then I change the data to characters and I get the same warning that you get.

library(caret)
TestDF <- data.frame(A = 1:4)
PreProcess1 <- preProcess(TestDF)
TestDF$A <- as.character(TestDF$A)
PreProcess2 <- preProcess(TestDF)
Warning in pre_process_options(method, column_types) :
  The following pre-processing methods were eliminated: 'center', 'scale'

Run str(df_train) before you run preProcess() and check the data type of you columns.

[lic]

The content in df_train is data. Please take a look at the image. After running the code, the data did not change. What is the reason for this？

[FJCC]

It is hard to tell from an image. It looks like you have three rows of headers. The read.csv() function will treat the first row as a header and include the other rows as part of your data. That will make all of the values characters. Did you run str(df_train) as I suggested?
If you do have three rows of headers, try skipping the first two with

df_train <- read.csv("sample_Standardization_train.csv", skip = 2)