Hi @WaleedBinAfzal,
Please take the following flow configuration for a reference.
The flow is triggered by When a record is created in Opportunities.
Followed by the action Get record. At here, please select Accounts for the Entity Name field, and for the Item identifier field, select dynamic content Account from the trigger.
Note: There is no Account Name dynamic content from the trigger When a record is created in Opportunities.
Then the action Send an email. In the Body field, select the Account name from the previous action Get record.


I have tested it on my side and it works fine.
Best regards,
Mabel Mao