Hi @Danny_Dicaprio ,
You want to give access to SP List or a specific SP list item ?
If you want to give access to a specific list item , then consider using grant access to an item or a folder action in Power Automate.
Now to give permissions to list you can use the below steps , all of them are sending an http request to SharePoint.
1. Break the Inheritance of the list permission , (if you don't want to give unique permission to the list then that is okay , you can directly add the user to a SP Group which is used in giving access to this list)
2. Get User principle Id
3. Give user the permission using the last POST method.
(please note if you want to use same expression then you have to name the action same as I have in my flow - see screenshot). Also ensure that there is no change in JSON schema and it fetches the Id property from the action output correctly.
//expression to get the usr principle Id
body('Send_an_HTTP_request_to_SharePoint_-_Get_User_Principle_Id')?['d']?['Id']
//expression to give the user the permission- 3rd HTTP call Uri property
_api/web/lists/getByTitle('Country')/roleassignments/addroleassignment(principalid=@{outputs('Compose_-_Get_User_Principle_Id')}, roledefid=1073741827)
//headers
{
"Accept ": "application/json;odata=verbose",
"content-Type": "application/json;odata=verbose"
}
S1
If you just want to add the user to a SP group without breaking permission , then you can use the below.

{
"__metadata": {
"type": "SP.User"
},
"LoginName":"i:0#.f|membership|user@company.com"
}
Please give this a thumbs up and mark this as a solution.
Thanks,
Sanmesh