5V regulator circuit with MOSFET. Will this catch on fire?
Ron=52 mOhm @ 4.5V seems appropriate until you compute load current of whatever you are applying.
Consider Pd*Rjc \$=\Delta T\$ rise (23’C/W = Rjc) for a SOT-23 as the temp. risk of burning your finger. Compute and then You decide if it exceeds 55’C on the case to your finger.
Fire is unlikely.
\$\Delta T_{case}= I^2 * 52 m\Omega * 23 ‘C/W\$
But you chose the wrong FET type instead of a logic level type with Vgs(th)=-0.9V MAX, you chose an old standard threshold TO-220 FET with 4V max threshold @ -250uA
So instead of 25mOhms you are not in full conduction yet and it appears from the plots that with a 10% drop in Vds from 5 or 0.5V at some high current like 2.4A or 12W this FET will be drawing constant (ish) current vs Vds meaning 10% of the sourced power is wasted in the FET and 1.2W with a thermal resistance from junction to ambient of almost 100’C (epoxy is an insulator) your junction temp is 120’c above ambient of 25’C or exceeding spec or “burning up electrons of material” thus satisfying the Darwinian Arhennius Law of reduced MTBF. So you need a 2 to 4W heatsink.
Next time choose a “Logic Level FET”
It won’t burn your finger but the junction is saying ouch at max power right now.