Well this is how i set up my powershell profile for ohmypwsh and auto complete for powershell 7

profile.ps1

Set-Item -Path Function:prompt -Value $Prompt -Force  
# get all themes 
$themes = Get-ChildItem -Path "~\AppData\Local\Programs\oh-my-posh\themes\*" -Include '*.omp.json' | Sort-Object Name 
# get a rendom theme
$theme = Get-Random -InputObject $themes.Name                                                                          
# initiate ohmyposh
oh-my-posh --init --shell pwsh --config ~/AppData/Local/Programs/oh-my-posh/themes/$theme | Invoke-Expression
# these are for auto complete of commands previously used
Import-Module PSReadLine
Set-PSReadLineOption -PredictionSource History
Set-PSReadLineOption -PredictionViewStyle ListView
Set-PSReadLineOption -EditMode Windows