Sure, you can use the /oauth2PermissionGrants endpoint: https://learn.microsoft.com/en-us/graph/api/oauth2permissiongrant-post?view=graph-rest-1.0&tabs=http
Or the New-MgServicePrincipalOauth2PermissionGrantByRef cmdlet from the Microsoft Graph SDK for PowerShell.
If you want to grant permissions to specific people only, use consentType value of "Principal" and specify a principalId ref value. Here's an example using the Graph explorer: