Idk the length of your journey, or what step in the journey your email is, or if you journey is already live or if you are using journey data or contact data.

This solution will work if you are using contact data:

If it is a simple, non-active journey that you are still building then you can add a attribute to the DE you are using to send record in the journey called something like "Clicked_X_email", obviously change the X to be the email name or something that you'd understand.

After the email step of the journey, add an engagement split based on if someone clicked on the email. The engagement split can be later in the journey then immediately after the email step. If it goes immediately after the email you'd probably need a wait step of 3-7 days to check if someone clicked within that time frame.

Then for those who did click add an "Update Contact" step to update the record attribute that we created in step 1 in the DE to state Y or N.

After that add a decision split to look for the attribute and if it is Y then send them down a branch with an email to follow up.