Step 1. Install ZSH

sudo pacman -S zsh

Step 2. Make ZSH default

chsh -s $(which zsh)

Step 3. Install font for powerlevel10k

Download these four ttf files and then install by double clicking each of them.
*MesloLGS NF Regular.ttf
*MesloLGS NF Bold.ttf
*MesloLGS NF Italic.ttf
*MesloLGS NF Bold Italic.ttf

Step 4. Log Out / Restart your machine

Step 5. Change Terminal font

First of all make sure your default terminal is ZSH by echo $SHELL. The return should be /usr/bin/zsh

Then from terminal goto Settings > Edit Current profile > Appearance > Choose > MesloLGS NF

Step 6. Powerlevel10k installation

Clone the repo

git clone --depth=1 https://github.com/romkatv/powerlevel10k.git ~/powerlevel10k 

Source the powerlevel10k theme script in your .zshrc

echo 'source ~/powerlevel10k/powerlevel10k.zsh-theme' >>~/.zshrc

Step 7. Configure Powerlevel10k

Close and reopen terminal. You should prompt with powerlevel10k configuration

If you don't get anything like this then run p10k configure

Step 8 (Optional). Fix "p10k configure: cannot create /usr/share/zsh/p10k.zsh because /usr/share/zsh is readonly" error

After running p10k configure if you get this error follow this step.

kate /usr/share/zsh/manjaro-zsh-prompt

You can use nano or other text editor instead of kate

Now put a # at the beginning of line 15 or copy and replace this at line 15 then save the file.

#[[ ! -f /usr/share/zsh/p10k.zsh ]] || source /usr/share/zsh/p10k.zsh

Now close and open terminal again to get the configuration wizard.

Step 9. Install Autosuggestion and Syntax Highlighting Plugin

git clone https://github.com/zsh-users/zsh-autosuggestions ~/.zsh/zsh-autosuggestions

echo 'source ~/.zsh/zsh-autosuggestions/zsh-autosuggestions.zsh'>>~/.zshrc 

git clone https://github.com/zsh-users/zsh-syntax-highlighting.git

echo 'source ./zsh-syntax-highlighting/zsh-syntax-highlighting.zsh'>>~/.zshrc 

Run these 4 command then restart the terminal and see the magic!!!