gistfile1.txt

$ini = @"
[INI-Version]
3
[Server Status]
"Online"
[Server Enabled]
True
[Server Host1]
"example.com"
[Server Host2]
"www.example.com";
[Enable Debug Logging]
True
[GUI Language]
"1033"
"@

$path = "$env:userprofile\test-(Get-Random).ini"

Set-Content -Path $path -Value $ini

$content = Get-Content -Path $path -Raw

$content2 = $content -replace '(?m)(?<key>^\[Server Host1\]\s+)(?<value>.*)','${key}my new value'

$content2

Remove-Item -Path $path