Should I buy external or internal SSD

Hi. I was planning to buy a hard drive because my laptop is out of storage. Based on my research Samsung T7 is a good external SSD, I'm planning to go with 500gb since I'm tight of budget. But I asked my sister and told me to buy internal ssd (to avoid lag and have efficient work). I don't really have knowledge when it comes to software so I don't know what to buy, I need more storage to continue with my projects. I'll be buying tomorrow so I need your thoughts about this.

For reference, I'm using laptop with 8gb ram only, but is upgradable to 16gb, thankfully I don't have problem rendering (I attached the details)

If you have any recommendations what's the best deal to buy for external SSD, please tell me (also if what cable should I buy, I saw some post that cable is also important). Or if I should just buy the internal one.

Thank you everyone!