Iterate through you sitecore environment and replace all the texts

FindAndReplace-Basic.ps1

# Minimal SPE find and replace across Single-Line Text, Multi-Line Text, Rich Text
# Static inputs
$FindText
$ReplaceText 
$ScopePaths    = "/sitecore/content"   # comma separated for multiple roots, for example "/sitecore/content/SiteA, /sitecore/content/SiteB"
$CaseSensitive = $true
$DryRun        = $false

if ([string]::IsNullOrWhiteSpace($FindText)) { throw "Find cannot be empty." }

# Prepare scope
$paths = $ScopePaths -split "," | ForEach-Object { $_.Trim() } | Where-Object { $_ }
if (-not $paths) { $paths = "/sitecore/content" }

# Prepare regex
$pattern = [regex]::Escape($FindText)
$regexOptions = if ($CaseSensitive) { [System.Text.RegularExpressions.RegexOptions]::None } else { [System.Text.RegularExpressions.RegexOptions]::IgnoreCase }

# Field types to update
$allowedTypes = @("Single-Line Text","Multi-Line Text","Rich Text")

# Counters
$totalItems   = 0
$itemsChanged = 0
$fieldsChanged = 0
$errCount = 0

# Database
$database = "master"

$stopwatch = [System.Diagnostics.Stopwatch]::StartNew()

# Collect all items under scope, all languages, all versions
$items = foreach ($root in $paths) {
    Get-ChildItem -Path "$database`:$root" -Recurse -Language * -ErrorAction SilentlyContinue
}

if (-not $items) { Write-Host "No items found in scope."; return }

Write-Host "Scanning $($items.Count) items in $database. DryRun=$DryRun CaseSensitive=$CaseSensitive"

# Faster bulk update and disable security
$bulk = New-Object Sitecore.Data.BulkUpdateContext
$sec  = New-Object Sitecore.SecurityModel.SecurityDisabler
try {
    foreach ($item in $items) {
        $totalItems++

        if ($item.Paths.Path -like "/sitecore/system*") { continue }

        $itemHadHits = $false
        $fieldHitsOnItem = 0

        $versions = $item.Versions.GetVersions($true)
        if (-not $versions -or $versions.Count -eq 0) { $versions = @($item) }

        foreach ($ver in $versions) {
            $editStarted = $false

            foreach ($field in $ver.Fields) {
                if ($null -eq $field) { continue }
                if ($field.ReadOnly) { continue }
                if ($field.Type -notin $allowedTypes) { continue }

                $current = [string]$field.Value
                if ([string]::IsNullOrEmpty($current)) { continue }

                if ([regex]::IsMatch($current, $pattern, $regexOptions)) {
                    $newValue = [regex]::Replace($current, $pattern, [System.Text.RegularExpressions.MatchEvaluator]{ param($m) $ReplaceText }, $regexOptions)

                    if (-not $DryRun) {
                        if (-not $ver.Editing.IsEditing) { $ver.Editing.BeginEdit() | Out-Null; $editStarted = $true }
                        $field.Value = $newValue
                    }

                    $itemHadHits = $true
                    $fieldHitsOnItem++
                }
            }

            if ($editStarted -and $ver.Editing.IsEditing) {
                $ver.Editing.EndEdit() | Out-Null
            }
        }

        if ($itemHadHits) {
            $fieldsChanged += $fieldHitsOnItem
            $itemsChanged++
            Write-Host "[HIT] $($item.Paths.Path) [$($item.Language)] fields: $fieldHitsOnItem"
        }

        if ($totalItems % 200 -eq 0) {
            $pct = [int](100 * $totalItems / [math]::Max(1, $items.Count))
            Write-Progress -Activity "Processing items" -Status "$totalItems scanned, $itemsChanged items with hits" -PercentComplete $pct
        }
    }
}
catch {
    $errCount++
    Write-Warning "Error: $_"
}
finally {
    if ($bulk) { $bulk.Dispose() }
    if ($sec)  { $sec.Dispose() }
    $stopwatch.Stop()
}

Write-Host ""
Write-Host "Done. Scanned items: $totalItems"
Write-Host "Items with hits: $itemsChanged"
Write-Host "Field replacements: $fieldsChanged"
Write-Host "Dry run: $DryRun"
Write-Host "Elapsed: $([int]$stopwatch.Elapsed.TotalSeconds)s"