It is probably just clogged with dust. Have someone clean out the dust or do it yourself. disassemble it and vacuum the dust out. Make sure to clean out all of the fans and give everything a good brush and vacuum.
The thermal paste applied to the processor (CPU) may be dried out. Open up the device, then remove the motherboard. Then remove the heat sink over the cpu and apply some thermal paste.
Thermal paste at Ifixit: [product|IF179-096|Thermal paste @ ifixit|new_window=true]
Thermal paste at Amazon: [link|https://ARCTIC MX-6 (8 g) - Ultimate Performance Thermal Paste for CPU, Consoles, Graphics Cards, laptops, Very high Thermal Conductivity, Long Durability, Non-Conductive, CPU Thermal Paste https://a.co/d/2yYvUE9|Arctic MX-6|new_window=true]
Thermal paste at Micro Center: [link|https://www.microcenter.com/product/617832/noctua-nt-h1-high-performance-tim-35g|Noctua thermal paste|new_window=true]
After you do these, install the app called Macs Fan Control which you can download at [link|https://crystalidea.com/macs-fan-control|this link|new_window=true]. You can control your computer’s fans with this app. If you don’t mind the noise, turn them up all the way, or a better option, put the fans at 30-50% speed for optimal cooling and lower noise.