It is possible to change the slew rate to slow by making changes in the GPIO_PRTx_PC register bit.
Refer to the page 769 of the register TRM for PSoC 4100 S Plus: https://www.cypress.com/file/405866/download .
I tried to recreate the project and was able to reproduce the issue.
With slew rate set to default (i.e fast) undershoot/ overshoot was observed.
with slew rate set as slow, the output was as shown below:
I have attached the project for reference. Please ensure that the rise time and fall time meet the required specification of the SPI when using slow slew rate.
Ekta - san
Thank you for your answer.