Playbook using STS

---
- hosts: local
  connection: local
  vars_files:
  - /root/creds.yml     #contains access_keys and secret keys for my msp account
  tasks:
  - name: Get STS credentials
    sts_assume_role:
       role_arn: "arn:aws:iam::xxxxxxxxxxx:role/MSPCrossAccount"   #Cross-account role_arn
       profile: test                                              #profile name that's mentioned in .aws/config file
       region: ap-south-1                                        
       role_session_name: ansible_test                                # you can specify any name in this field
    register: assumed_role
  - debug:
      msg: "{{ assumed_role }}"
  - name: get instance info
    ec2_instance_facts:
      aws_access_key: "{{ assumed_role.sts_creds.access_key }}"
      aws_secret_key: "{{ assumed_role.sts_creds.secret_key }}"
      security_token: "{{ assumed_role.sts_creds.session_token }}"
      filters:
        "tag:Environment": prod
    register: out
  - debug:
      msg: "{{ out }}"

Make sure you have valid entries in .aws/config file. Below is the example
[profile test]
role_arn = arn:aws:iam::xxxxxxxxxxxxx:role/MSPCrossAccount
source_profile = msp # this points to your access keys and secret keys in .aws/credential file
region = ap-south-1