I have 50 post-deployment steps and I need to perform on UAT, Pre_Production, and Production. Is there any way that we can automate the steps?
Large numbers of post-deployment steps usually reflect a weak source control or change control program. Unfortunately, that means that the solution is architectural: there will be a need for a significant investment in product, and possibly tooling as well, to eliminate these steps.
For example, if post-deployment steps include making manual changes to Page Layouts, the solution is to make those changes as part of development, version control them, and deploy them to production alongside other application changes.
However, if the organization is used to being able to make page layout changes directly in Production, this could be a significant, and potentially disruptive, shift.
Many tools, both commercial and otherwise, are available to facilitate a comprehensive source control/continuous integration/continuous deployment strategy. It's essentially always going to be a fact, though, that none of these tools will provide a push-button fix to correct a specific problem, like this one, that is representative of a fundamental weakness in architecture. You're going to have to make some level of change to your development strategy, org pipeline, source control, etc., in order to achieve a genuine fix.
We've used the SandboxPostCopy interface to create a script that runs after the sandbox is created.
One potential gotcha: the script runs as the "Automated User". So make sure any test records you create have a specified owner.
Some things can't be updated easily via apex. I'd be interesting in knowing what specific steps are being done. But in any case, you may be able to cut your 50 steps down to <5.
I doubt that any product out there provides one click solution to automate the post deployment steps. You could explore paid solutions likes AutoRABIT, BlueCanvas etc., but they won't provide complete automation either. If the post deployment steps are something that can be performed by APEX or LIGHTNING, then you could develop custom solutions.