The Irish face the Qataris at Bury FC's Gigg Lane on Friday (6.00pm) then travel to Andorra for their second UEFA U21 Championships Qualifying Round Group 2 fixture on Tuesday, September 8 (4.00pm Irish).
King's charges beat Andorra 1-0 at Waterford's RSC in their opening qualifier in March thanks to a goal by Ipswich Town's former Shelbourne winger Dylan Connolly.
"Qatar gives everybody a chance to play. It's a training opportunity for both sides. The last time we played were a physical side, well organised and a good challenge," said King.
"That game will be important to help us bed into how we want to play in the competitive game. There's a great variation in the clubs, leagues and systems the players are playing in so the sooner we get together the better."
King has handed first U21 call-ups to QPR winger Reece Grego-Cox and West Ham United midfielder Josh Cullen and he is looking forward to working with the duo.
"They are quite young but already they have both played Premier League football which is a great achievement for players that age. They'll get every chance and every support with us and hopefully it'll all work out well for them at this level.
"The whole thing is to go to Andorra as well-prepared as possible. We had lots of possession against them in Waterford but struggled to turn that into enough goal-scoring opportunities but since then they've beaten Lithuania so we know it's not going to be an easy game in their place.
"We've a few injuries from the Waterford game too but the new players coming in means the competition is stiff and we are looking forward to these game. "
REPUBLIC OF IRELAND U21s:
Daniel Rogers (Aberdeen - on loan Falkirk)
Eric Grimes (Leeds United)
Thomas Hoban (Watford)
Glen Rea (Brighton - on-loan at Southend)
Darragh Lenihan (Blackburn Rovers)
Shane Griffin (Reading)
Alan Browne (Preston North End)
Jack Connors (Dagenham)
Dylan Connolly (Ipswich Town)
Sean Kavanagh (Fulham)
Callum O'Dowda (Oxford United)
Reece Grego-Cox (QPR)
Brian Lenihan (Hull City)
Sean Long (Reading)
Conor Wilkinson (Barnsley)
Shamir Goodwin (Crawley Town)
Sean Maguire (Dundalk)
Sam Byrne (Everton)
Josh Cullen (West Ham)
FIXTURES
Friday, September 4
International Friendly
Qatar U23 v Republic of Ireland, Gigg Lane, Bury (6.00pm)
Tuesday, September 8
UEFA U21 Championships Qualifying Round Group 2
Andorra v Republic of Ireland, Andorra Le Vella, Andorra (4.00pm)