Xampp does not use multiple version of PHP out of the box. However, you may have projects that use different PHP versions.

Let's say you are currently on PHP 8 and you want to install PHP 7.

Here is how you install the different PHP versions you require:

Step 1. Go to  windows.php.net to download PHP version 

Based on your xampp set up you will have to choose NTS or TS version which stands for Non-Thread Safe and Thread Safe. You can check PhpInfo to verify.

Also x64 or x86 based on CPU architecture. 

Step 2. Extract the file and copy into the xampp directory

C:\xampp\php7_4

Step 3. configure php.ini file

Open C:\xampp\php7_4\php.ini, if that file does not exist you can rename php.ini-production into php.ini.

Then uncomment the line below:

extension_dir = "ext"

Also enable all the other required extension needed:

extension=bz2
extension=curl
;extension=ffi
;extension=ftp
extension=fileinfo
extension=gd
extension=gettext
;extension=gmp
;extension=intl
;extension=imap
;extension=ldap
extension=mbstring
extension=exif      ; Must be after mbstring as it depends on it
extension=mysqli
;extension=oci8_12c  ; Use with Oracle Database 12c Instant Client
;extension=oci8_19  ; Use with Oracle Database 19 Instant Client
;extension=odbc
;extension=openssl
;extension=pdo_firebird
extension=pdo_mysql
;extension=pdo_oci
;extension=pdo_odbc
;extension=pdo_pgsql
extension=pdo_sqlite
;extension=pgsql
;extension=shmop

; The MIBS data available in the PHP distribution must be installed.
; See http://www.php.net/manual/en/snmp.installation.php
;extension=snmp

;extension=soap
;extension=sockets
;extension=sodium
;extension=sqlite3
;extension=tidy
;extension=xsl

;zend_extension=opcache

 Step 4. Configure Apache

Open Xampp control panel and click config button, then click Apache (httpd-xampp-conf)

The file httpd-xampp-.conf will open. Place the code snippet below:

ScriptAlias /php74/ "C:/xampp/php74/"
Action application/x-httpd-php74-cgi "/php74/php-cgi.exe"

    AllowOverride None
    Options None
    Require all denied
    
          Require all granted
    


Listen 8888

    UnsetEnv PHPRC
    
        php_flag engine off
        SetHandler application/x-httpd-php74
        Action application/x-httpd-php74 "/php74/php-cgi.exe"
    

Step 5. Restart Apache

Restart Apache and point your project to the port:

http://localhost:8888/project