1. Installing PECL :
   sudo apt-get install autoconf zlib1g-dev php-dev php-pear

2. Installing Composer ( skip if already installed ) :
   curl -sS https://getcomposer.org/installer | php
sudo mv composer.phar /usr/local/bin/composer

3. Installing extension php grcp :
   sudo pecl install grpc

4. Edit your php.ini in /etc/php/{7.4 or 8.0 or other php version }/cli/php.ini and add extension=grpc.so

Good luck