Is there any way to run a script inside alredy existing infrastructre using terraform

I want to run a script using terraform inside an existing instance on any cloud which is pre-created .The instance was created manually , is there any way to push my script to this instance and run it using terraform ?
if yes ,then How can i connect to the instance using terraform and push my script and run it ?

I believe ansible is a better option to achieve this easily.

Refer the example give here -
https://docs.ansible.com/ansible/latest/modules/script_module.html

1. Create a .tf file and describe your already existing resource (e.g. VM) there
2. Import existing thing using terraform import
3. If this is a VM then add your script to remote machine using file provisioner and run it using remote-exec - both steps are described in Terraform file, no manual changes needed
4. Run terraform plan to see if expected changes are ok, then terraform apply if plan was fine

Terraform's core mission is to create, update, and destroy long-lived infrastructure objects. It is not generally concerned with the software running in the compute instances it deploys. Instead, it generally expects each object it is deploying to behave as a sort of specialized "appliance", either by being a managed service provided by your cloud vendor or because you've prepared your own machine image outside of Terraform that is designed to launch the relevant workload immediately when the system boots. Terraform then just provides the system with any configuration information required to find and interact with the surrounding infrastructure.

A less-ideal way to work with Terraform is to use its provisioners feature to do late customization of an image just after it's created, but that's considered to be a last resort because Terraform's lifecycle is not designed to include strong support for such a workflow, and it will tend to require a lot more coupling between your main system and its orchestration layer.

Terraform has no mechanism intended for pushing arbitrary files into existing virtual machines. If your virtual machines need ongoing configuration maintenence after they've been created (by Terraform or otherwise) then that's a use-case for traditional configuration management software such as Ansible, Chef, Puppet, etc, rather than for Terraform.